Refactored scope names and updated docs to reflect this

jupyterhub/services/auth.py

@@ -835,8 +835,8 @@ class HubAuthenticated:
       which in turn is set by $JUPYTERHUB_OAUTH_SCOPES
       Default values include:
       - 'access:services', 'access:services!service={service_name}' for services
-      - 'access:users:servers', 'access:users:servers!user={user}',
-        'access:users:servers!server={user}/{server_name}'
+      - 'access:servers', 'access:servers!user={user}',
+        'access:servers!server={user}/{server_name}'
         for single-user servers
 
     If hub_scopes is not used (e.g. JupyterHub 1.x),