Change "client" to "SDK" (#149)

## Problem

We are inconsistent in how we refer to our client libraries.

## Solution

As we mostly refer to our "SDKs" rather than our "clients", we've
updated our docs to prefer "SDK". This PR makes equivalent updates to
the Java SDK README.

Addresses: https://app.asana.com/0/1206419570114940/1207978475519546/f

## Type of Change

- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] This change requires a documentation update
- [ ] Infrastructure change (CI configs, etc)
- [x] Non-code change (docs, etc)
- [ ] None of the above: (explain here)

## Test Plan

Describe specific steps for validating this change.

Author: jseldess

README.md

@@ -1,6 +1,6 @@
-# Pinecone Java Client
+# Pinecone Java SDK
 
-The Pinecone Java client lets JVM applications interact with Pinecone services.
+The Pinecone Java SDK lets JVM applications interact with Pinecone services.
 
 ## Requirements
 
@@ -28,8 +28,8 @@ implementation "io.pinecone:pinecone-client:1.2.2"
 
 [comment]: <> (^ [pc:VERSION_LATEST_RELEASE])
 
-Alternatively, you can use our standalone uberjar [pinecone-client-2.0.0-all.jar](https://repo1.maven.org/maven2/io/pinecone/pinecone-client/2.0.0/pinecone-client-2.0.0-all.jar), which bundles the pinecone
-client and all dependencies together. You can include this in your classpath like you do with any 3rd party JAR without
+Alternatively, you can use our standalone uberjar [pinecone-client-2.0.0-all.jar](https://repo1.maven.org/maven2/io/pinecone/pinecone-client/2.0.0/pinecone-client-2.0.0-all.jar), which bundles the Pinecone
+SDK and all dependencies together. You can include this in your classpath like you do with any 3rd party JAR without
 having to obtain the *pinecone-client* dependencies separately.
 
 [comment]: <> (^ [pc:VERSION_LATEST_RELEASE])