Update README.rst (aws#6533)

* Update README.rst

Punctuation changes

README.rst

@@ -32,12 +32,15 @@ The aws-cli package works on Python versions:
 -  3.9.x and greater
 -  3.10.x and greater
 
-On 01/15/2021 deprecation for Python 2.7 was announced and support was dropped
+Notices
+~~~~~~~
+
+On 01/15/2021, deprecation for Python 2.7 was announced and support was dropped
 on 07/15/2021. To avoid disruption, customers using the AWS CLI on Python 2.7 may
 need to upgrade their version of Python or pin the version of the AWS CLI. For
 more information, see this `blog post <https://aws.amazon.com/blogs/developer/announcing-end-of-support-for-python-2-7-in-aws-sdk-for-python-and-aws-cli-v1/>`__.
 
-On 10/29/2020 support for Python 3.4 and Python 3.5 was deprecated and
+On 10/29/2020, support for Python 3.4 and Python 3.5 was deprecated and
 support was dropped on 02/01/2021. Customers using the AWS CLI on
 Python 3.4 or 3.5 will need to upgrade their version of Python to
 continue receiving feature and security updates. For more information,
@@ -88,7 +91,7 @@ or for your user:
    $ python -m pip install --user awscli
 
 If you have the aws-cli package installed and want to upgrade to the
-latest version you can run:
+latest version, you can run:
 
 ::