Add html meta description to service and operation pages

[kdaily]

Issue #, if available:

NA

Description of changes:

To all top level service documentation and individual operation pages, add an HTML meta directive.

This also adds in some extra newlines to account for new reStructuredText directives that would have not been spaced properly and then rendered directly as text.

The doc_meta_description is added to the main CLIDocumentEventHandler so that child classes that inherit it that are not for service or operations do not add the directive to the RST files (like topics or CLI configuration).

Added a test for a service and operation page to assert some of the expected text is included in the document.

RST file before

[ :ref:`aws <cli:aws>` . :ref:`bedrock-agentcore <cli:aws bedrock-agentcore>` ]

.. _cli:aws bedrock-agentcore batch-create-memory-records:


***************************
batch-create-memory-records
***************************

RST file after

[ :ref:`aws <cli:aws>` . :ref:`bedrock-agentcore <cli:aws bedrock-agentcore>` ]

.. meta::
   :description: Use the AWS CLI 1.42.59 to run the bedrock-agentcore batch-create-memory-records command.


.. _cli:aws bedrock-agentcore batch-create-memory-records:


***************************
batch-create-memory-records
***************************```

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.34%. Comparing base (68039fa) to head (6ca4e3b).
⚠️ Report is 353 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #9824      +/-   ##
===========================================
- Coverage    93.40%   93.34%   -0.06%     
===========================================
  Files          211      209       -2     
  Lines        17012    16823     -189     
===========================================
- Hits         15890    15704     -186     
+ Misses        1122     1119       -3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.