Update README.rst file (#27031)

* Update supported Python version in readme

Match the current supported version and also links to the version support policy

* Update badges

remove older travis badge
update main branch on Azure DevOps build status badge

README.rst

@@ -7,11 +7,8 @@ Microsoft Azure SDK for Python
 .. image:: https://img.shields.io/pypi/pyversions/azure.svg?maxAge=2592000
     :target: https://pypi.python.org/pypi/azure/
 
-.. image:: https://dev.azure.com/azure-sdk/public/_apis/build/status/46?branchName=master
-    :target: https://dev.azure.com/azure-sdk/public/_build/latest?definitionId=46&branchName=master
-
-.. image:: https://travis-ci.org/Azure/azure-sdk-for-python.svg?branch=master
-    :target: https://travis-ci.org/Azure/azure-sdk-for-python
+.. image:: https://dev.azure.com/azure-sdk/public/_apis/build/status/46?branchName=main
+    :target: https://dev.azure.com/azure-sdk/public/_build/latest?definitionId=46&branchName=main
 
 .. image:: https://img.shields.io/badge/dependencies-analyzed-blue.svg
     :target: https://azuresdkartifacts.blob.core.windows.net/azure-sdk-for-python/dependencies/dependencies.html
@@ -22,7 +19,7 @@ access Management (Virtual Machines, ...) or Runtime (ServiceBus using HTTP, Bat
 Complete feature list of this repo and where to find Python packages not in this repo can be found on our 
 `Azure SDK for Python documentation <https://docs.microsoft.com/python/api/overview/azure/?view=azure-python>`__.
 
-The SDK supports Python 2.7, 3.4, 3.5 and 3.6.
+The SDK supports Python 3.7 or later. For more details, please read our page on `Azure SDK for Python version support policy <https://github.com/Azure/azure-sdk-for-python/wiki/Azure-SDKs-Python-version-support-policy>`__.
 
 If you're currently using the ``azure`` package < 1.0 then please read important information in `this issue <https://github.com/Azure/azure-sdk-for-python/issues/440>`__.