Integrate presence from hotfixes (#3694)

docs/workers.rst

@@ -241,6 +241,14 @@ regular expressions::
 
     ^/_matrix/client/(api/v1|r0|unstable)/keys/upload
 
+If ``use_presence`` is False in the homeserver config, it can also handle REST
+endpoints matching the following regular expressions::
+
+    ^/_matrix/client/(api/v1|r0|unstable)/presence/[^/]+/status
+
+This "stub" presence handler will pass through ``GET`` request but make the
+``PUT`` effectively a no-op.
+
 It will proxy any requests it cannot handle to the main synapse instance. It
 must therefore be configured with the location of the main instance, via
 the ``worker_main_http_uri`` setting in the frontend_proxy worker configuration