Various style and formatting fixes

Fixes cockroachdb#3249.

Summary of changes:

- Changed all headings to sentence case

- Added clipboard copy widget to code samples

- Fixed a few contractions spotted by the prose linter

- Fixed 2 broken diagrams which needed wrapping in `div` tags

Author: rmloveland

v2.1/explain.md

@@ -8,7 +8,7 @@ The `EXPLAIN` [statement](sql-statements.html) returns CockroachDB's query plan
 
 <div id="toc"></div>
 
-## Explainable Statements
+## Explainable statements
 
 You can `EXPLAIN` on the following statements:
 
@@ -33,7 +33,7 @@ You can `EXPLAIN` on the following statements:
 - [`UPDATE`](update.html)
 - [`UPSERT`](upsert.html)
 
-## Query Optimization
+## Query optimization
 
 Using `EXPLAIN`'s output, you can optimize your queries by taking the following points into consideration:
 
@@ -70,7 +70,7 @@ The user requires the appropriate [privileges](privileges.html) for the statemen
 
 {{site.data.alerts.callout_danger}}<code>EXPLAIN</code> also includes other modes besides query plans that are useful only to CockroachDB developers, which are not documented here.{{site.data.alerts.end}}
 
-## Success Responses
+## Success responses
 
 Successful `EXPLAIN` statements return tables with the following columns:
 
@@ -84,7 +84,7 @@ Successful `EXPLAIN` statements return tables with the following columns:
 
 ## Examples
 
-### Default Query Plans
+### Default query plans
 
 By default, `EXPLAIN` includes the least detail about the query plan but can be
 useful to find out which indexes and index key ranges are used by a query:
@@ -113,7 +113,7 @@ index you are scanning (in this case, a full table scan). For more
 information on indexes and key ranges, see the
 [example](#find-the-indexes-and-key-ranges-a-query-uses) below.
 
-### `EXPRS` Option
+### `EXPRS` option
 
 The `EXPRS` option includes SQL expressions that are involved in each processing stage, providing more granular detail about which portion of your query is represented at each level:
 
@@ -135,7 +135,7 @@ The `EXPRS` option includes SQL expressions that are involved in each processing
 +-----------+--------+-------------+
 ~~~
 
-### `METADATA` Option
+### `METADATA` option
 
 The `METADATA` option includes detail about which columns are being used by each
 level, as well as properties of the result set on that level:
@@ -211,7 +211,7 @@ that are known to have the same value on all rows. For example:
 This indicates that on any row, column `a` has the same value with column `e`,
 and that all rows have the same value on column `c`.
 
-### `QUALIFY` Option
+### `QUALIFY` option
 
 `QUALIFY` uses `<table name>.<column name>` notation for columns in the query plan. However, `QUALIFY` must be used with `EXPRS` to show the SQL values used:
 
@@ -261,7 +261,7 @@ You can contrast this with the same statement not including the `QUALIFY` option
 +-------+--------+----------+-------------+
 ~~~
 
-### `VERBOSE` Option
+### `VERBOSE` option
 
 The `VERBOSE` option is an alias for the combination of `EXPRS`, `METADATA`, and `QUALIFY` options:
 
@@ -294,7 +294,7 @@ The `VERBOSE` option is an alias for the combination of `EXPRS`, `METADATA`, and
 +---------------------+-------+--------+----------------+------------------+-----------------------+------------------------------+
 ~~~
 
-### `TYPES` Option
+### `TYPES` option
 
 The `TYPES` mode includes the types of the values used in the query plan, and implies the `METADATA` and `EXPRS` options as well:
 
@@ -316,7 +316,7 @@ The `TYPES` mode includes the types of the values used in the query plan, and im
 +-----------+-------+------+--------+-----------------------------+----------------+------------------------------+
 ~~~
 
-### Find the Indexes and Key Ranges a Query Uses
+### Find the indexes and key ranges a query uses
 
 You can use `EXPLAIN` to understand which indexes and key ranges queries use,
 which can help you ensure a query isn't performing a full table scan.

v2.1/export.md

@@ -12,13 +12,13 @@ Using the [CockroachDB distributed execution engine](https://www.cockroachlabs.c
 
 <div id="toc"></div>
 
-## Export File Location
+## Export file location
 
 You can use remote cloud storage (Amazon S3, Google Cloud Platform, etc.) to store the exported CSV data. Alternatively, you can use an [HTTP server](create-a-file-server.html) accessible from all nodes.
 
 For simplicity's sake, it's **strongly recommended** to use cloud/remote storage for the data you want to export. Local files are supported; however, they must be accessible identically from all nodes in the cluster.
 
-## Cancelling Export
+## Cancelling export
 
 After the export has been initiated, you can cancel it with [`CANCEL QUERY`](cancel-query.html).
 
@@ -41,15 +41,15 @@ Only the `root` user can run [`EXPORT`](export.html).
 | `select_stmt` | Specify the query whose result you want to export to CSV format. |
 | `table_name` | Specify the name of the table you want to export to CSV format. |
 
-### Export File URL
+### Export file URL
 
 URLs for the file directory location you want to export to must use the following format:
 
 {% include external-urls-v2.0.md %}
 
 You can specify the base directory where you want to store the exported .csv files. CockroachDB will create several files in the specified directory with programmatically generated names (e.g., n1.1.csv, n1.2.csv, n2.1.csv, ...).
 
-### Export Options
+### Export options
 
 You can control the [`EXPORT`](export.html) process's behavior using any of the following key-value pairs as a `kv_option`.
 
@@ -105,7 +105,7 @@ Convert SQL *NULL* values so they match the specified string.
 
 ## Examples
 
-### Export a Table
+### Export a table
 
 {% include copy-clipboard.html %}
 ~~~ sql
@@ -114,7 +114,7 @@ Convert SQL *NULL* values so they match the specified string.
   WITH delimiter = '|' FROM TABLE bank.customers;
 ~~~
 
-### Export Using a `SELECT` Statement
+### Export using a `SELECT` statement
 
 {% include copy-clipboard.html %}
 ~~~ sql
@@ -123,14 +123,14 @@ Convert SQL *NULL* values so they match the specified string.
   FROM SELECT * FROM bank.customers WHERE id >= 100;
 ~~~
 
-### Non-Distributed Export Using the SQL Shell
+### Non-distributed export using the SQL shell
 
 {% include copy-clipboard.html %}
 ~~~ shell
 $ cockroach sql -e "SELECT * from bank.customers WHERE id>=100;" --format=csv > my.csv
 ~~~
 
-## Known Limitation
+## Known limitation
 
 `EXPORT` may fail with an error if the SQL statements are incompatible with DistSQL. In that case, use the [non-enterprise feature to export tabular data in CSV format](#non-distributed-export-using-the-sql-shell).
 

v2.1/foreign-key.md

@@ -17,7 +17,7 @@ For example, if you create a foreign key on `orders.customer` that references `c
 
 ## Details
 
-### Rules for Creating Foreign Keys
+### Rules for creating foreign keys
 
 **Foreign Key Columns**
 
@@ -37,7 +37,7 @@ For example, if you create a foreign key on `orders.customer` that references `c
 - Referenced columns must contain only unique sets of values. This means the `REFERENCES` clause must use exactly the same columns as a [Unique](unique.html) or [Primary Key](primary-key.html) constraint on the referenced table. For example, the clause `REFERENCES tbl (C, D)` requires `tbl` to have either the constraint `UNIQUE (C, D)` or `PRIMARY KEY (C, D)`.
 - In the `REFERENCES` clause, if you specify a table but no columns, CockroachDB references the table's primary key. In these cases, the Foreign Key constraint and the referenced table's primary key must contain the same number of columns.
 
-### _NULL_ Values
+### _NULL_ values
 
 Single-column foreign keys accept _NULL_ values.
 
@@ -50,7 +50,7 @@ For example, if you have a Foreign Key constraint on columns `(A, B)` and try to
 
 However, allowing _NULL_ values in either your foreign key or referenced columns can degrade their referential integrity. To avoid this, you can use the [Not Null constraint](not-null.html) on both sets of columns when [creating your tables](create-table.html). (The Not Null constraint cannot be added to existing tables.)
 
-### Foreign Key Actions 
+### Foreign key actions
 
 When you set a foreign key constraint, you can control what happens to the constrained column when the column it's referencing (the foreign key) is deleted or updated.
 
@@ -77,7 +77,7 @@ Foreign Key constraints can be defined at the [table level](#table-level). Howev
 
 {{site.data.alerts.callout_info}}You can also add the Foreign Key constraint to existing tables through <a href="add-constraint.html#add-the-foreign-key-constraint-with-cascade"><code>ADD CONSTRAINT</code></a>.{{site.data.alerts.end}}
 
-### Column Level
+### Column level
 
 <section>{% include sql/{{ page.version.version }}/diagrams/foreign_key_column_level.html %}</section>
 
@@ -94,6 +94,7 @@ Foreign Key constraints can be defined at the [table level](#table-level). Howev
 
 **Example**
 
+{% include copy-clipboard.html %}
 ~~~ sql
 > CREATE TABLE IF NOT EXISTS orders (
     id INT PRIMARY KEY,
@@ -104,7 +105,7 @@ Foreign Key constraints can be defined at the [table level](#table-level). Howev
 ~~~
 {{site.data.alerts.callout_danger}}<code>CASCADE</code> does not list objects it drops or updates, so it should be used cautiously.{{site.data.alerts.end}}
 
-### Table Level
+### Table level
 
 <section>{% include sql/{{ page.version.version }}/diagrams/foreign_key_table_level.html %}</section>
 
@@ -120,6 +121,7 @@ Foreign Key constraints can be defined at the [table level](#table-level). Howev
 
 **Example**
 
+{% include copy-clipboard.html %}
 ~~~ sql
 CREATE TABLE packages (
     customer INT,
@@ -134,9 +136,9 @@ CREATE TABLE packages (
   ;
 ~~~
 
-## Usage Examples
+## Usage examples
 
-### Use a Foreign Key Constraint with Default Actions
+### Use a foreign key constraint with default actions
 
 In this example, we'll create a table with a foreign key constraint with the default [actions](#foreign-key-actions) (`ON UPDATE NO ACTION ON DELETE NO ACTION`).
 

v2.1/frequently-asked-questions.md

@@ -92,7 +92,7 @@ For more details, learn our [basic CockroachDB SQL statements](learn-cockroachdb
 
 ## Does CockroachDB support distributed transactions?
 
-Yes. CockroachDB distributes transactions across your cluster, whether it’s a few servers in a single location or many servers across multiple datacenters. Unlike with sharded setups, you don’t need to know the precise location of data; you just talk to any node in your cluster and CockroachDB gets your transaction to the right place seamlessly. Distributed transactions proceed without downtime or additional latency while rebalancing is underway. You can even move tables – or entire databases – between data centers or cloud infrastructure providers while the cluster is under load.
+Yes. CockroachDB distributes transactions across your cluster, whether it’s a few servers in a single location or many servers across multiple datacenters. Unlike with sharded setups, you do not need to know the precise location of data; you just talk to any node in your cluster and CockroachDB gets your transaction to the right place seamlessly. Distributed transactions proceed without downtime or additional latency while rebalancing is underway. You can even move tables – or entire databases – between data centers or cloud infrastructure providers while the cluster is under load.
 
 ## Do transactions in CockroachDB guarantee ACID semantics?
 

v2.1/functions-and-operators.md

@@ -10,15 +10,15 @@ CockroachDB supports the following SQL functions and operators for use in [scala
 
 <div id="toc"></div>
 
-## Special Syntax Forms
+## Special syntax forms
 
 The following syntax forms are recognized for compatibility with the
 SQL standard and PostgreSQL, but are equivalent to regular built-in
 functions:
 
 {% include sql/{{ page.version.version }}/function-special-forms.md %}
 
-## Conditional and Function-Like Operators
+## Conditional and function-like operators
 
 The following table lists the operators that look like built-in
 functions but have special evaluation rules:
@@ -36,11 +36,11 @@ functions but have special evaluation rules:
 | `NULLIF(...)` | [Return `NULL` conditionally](scalar-expressions.html#nullif-expressions) |
 | `ROW(...)` | [Tuple Constructor](scalar-expressions.html#tuple-constructor) |
 
-## Built-in Functions
+## Built-in functions
 
 {% include sql/{{ page.version.version }}/functions.md %}
 
-## Aggregate Functions
+## Aggregate functions
 
 {% include sql/{{ page.version.version }}/aggregates.md %}
 
@@ -102,7 +102,7 @@ The following table lists all CockroachDB operators from highest to lowest prece
 
 [Multi-valued]: scalar-expressions.html#multi-valued-comparisons
 
-### Supported Operations
+### Supported operations
 
 {% include sql/{{ page.version.version }}/operators.md %}