add microsoft-graph backend

docs/backends/index.rst

@@ -111,6 +111,7 @@ Social backends
    mediawiki
    meetup
    mendeley
+   microsoftgraph
    mineid
    mixcloud
    moves

docs/backends/microsoftgraph.rst

@@ -0,0 +1,25 @@
+Microsoft Graph
+===============
+
+
+1. Go to `Azure portal`_ and create an application. 
+
+2. Fill App Id and Secret in your project settings::
+
+    SOCIAL_AUTH_MICROSOFT_GRAPH_KEY = '...'
+    SOCIAL_AUTH_MICROSOFT_GRAPH_SECRET = '...'
+
+
+3. Enable the backend::
+
+    SOCIAL_AUTH_AUTHENTICATION_BACKENDS = (
+        ...
+        'social_core.backends.microsoft.MicrosoftOAuth2',
+        ...
+    )
+
+`Register an application with the Microsoft identity platform`_.
+
+.. _Azure portal: https://portal.azure.com/
+.. _Register an application with the Microsoft identity platform: https://docs.microsoft.com/en-us/azure/active-directory/develop/quickstart-register-app
+