Python 2.7 warning (#20895)

* Update README.md

* Update README.md

* Update README.md

* Update README.md

* Update README.md

* Update README.md

Author: Rodrigo Souza

sdk/cosmos/azure-cosmos/README.md

@@ -15,6 +15,10 @@ Use the Azure Cosmos DB SQL API SDK for Python to manage databases and the JSON
 
 ## Getting started
 
+### Important update on Python 2.x Support
+
+New releases of this SDK won't support Python 2.x starting January 1st, 2022. Please check the [CHANGELOG](https://github.com/Azure/azure-sdk-for-python/blob/main/sdk/cosmos/azure-cosmos/CHANGELOG.md) for more information.
+
 ### Prerequisites
 
 * Azure subscription - [Create a free account][azure_sub]