docs: update azuread docs about auth_state_groups_key

docs/source/tutorials/provider-specific-setup/providers/azuread.md

@@ -35,16 +35,14 @@ be relevant to read more about in the configuration reference:
 ## Loading user groups
 
 The `AzureAdOAuthenticator` can load the group-membership of users from the access token.
-This is done by setting the `AzureAdOAuthenticator.groups_claim` to the name of the claim that contains the
-group-membership.
 
 ```python
 c.JupyterHub.authenticator_class = "azuread"
 
 # {...} other settings (see above)
 
 c.AzureAdOAuthenticator.manage_groups = True
-c.AzureAdOAuthenticator.user_groups_claim = 'groups'  # this is the default
+c.AzureAdOAuthenticator.auth_state_groups_key = 'user.groups'
 ```
 
 This requires Azure AD to be configured to include the group-membership in the access token.