[Docs] Include a code example for rack-awareness

[GeoffMontee]

Starting with 3.28.0, our release of the ScyllaDB Python driver supports rack-awareness.

We have some limited documentation about this feature here:

https://python-driver.docs.scylladb.com/stable/api/cassandra/policies.html#cassandra.policies.RackAwareRoundRobinPolicy

https://github.com/scylladb/python-driver/blob/master/docs/api/cassandra/policies.rst

Perhaps we could include a more complete example in the documentation. For example:

from cassandra.cluster import Cluster, ExecutionProfile, EXEC_PROFILE_DEFAULT
from cassandra.policies import RackAwareRoundRobinPolicy, DowngradingConsistencyRetryPolicy
from cassandra.query import tuple_factory

profile = ExecutionProfile(
    load_balancing_policy=RackAwareRoundRobinPolicy('AWS_US_EAST_1', 'us-east-1a'),
    retry_policy=DowngradingConsistencyRetryPolicy(),
    consistency_level=ConsistencyLevel.LOCAL_QUORUM,
    serial_consistency_level=ConsistencyLevel.LOCAL_SERIAL,
    request_timeout=15,
    row_factory=tuple_factory
)
cluster = Cluster(['192.168.1.1', '192.168.1.2','192.168.1.3'], execution_profiles={EXEC_PROFILE_DEFAULT: profile})
session = cluster.connect()

We might also want to include a disclaimer about AWS specifically, where AZs do not have consistent names between different AWS accounts. Maybe the documentation can provide more detailed guidance about this or refer to the AWS documentation that mentions how to obtain the internal AZ IDs.

[GeoffMontee]

To implement this change, would we want to put the example on the "Getting Started" page, where we have other connection-related examples?:

https://python-driver.docs.scylladb.com/stable/getting-started.html

https://github.com/scylladb/python-driver/blob/master/docs/getting-started.rst

There is also a page about "Execution Profiles", which talks about the nested load balancing policy, so that page might be relevant to this topic:

https://python-driver.docs.scylladb.com/stable/execution-profiles.html

https://github.com/scylladb/python-driver/blob/master/docs/execution-profiles.rst

Since rack awareness is a Scylla-specific feature, we might also want to mention the feature on the "Scylla Specific Features" page:

https://python-driver.docs.scylladb.com/stable/scylla-specific.html

https://github.com/scylladb/python-driver/blob/master/docs/scylla-specific.rst

[GeoffMontee]

We might also want to include a disclaimer about AWS specifically, where AZs do not have consistent names between different AWS accounts. Maybe the documentation can provide more detailed guidance about this or refer to the AWS documentation that mentions how to obtain the internal AZ IDs.

Here's the corresponding AWS Documentation page: Availability Zone IDs for your AWS resources