Add Python 2 deprecation on front page (Azure#20799)

Author: lmazuel

README.md

@@ -4,6 +4,10 @@
 
 This repository is for active development of the Azure SDK for Python. For consumers of the SDK we recommend visiting our [public developer docs](https://docs.microsoft.com/python/azure/) or our versioned [developer docs](https://azure.github.io/azure-sdk-for-python).
 
+## _Disclaimer_
+
+_Azure SDK Python packages support for Python 2.7 is ending 01 January 2022. For more information and questions, please refer to https://github.com/Azure/azure-sdk-for-python/issues/20691_
+
 ## Getting started
 
 For your convenience, each service has a separate set of libraries that you can choose to use instead of one, large Azure package. To get started with a specific library, see the `README.md` (or `README.rst`) file located in the library's project folder.