Update worker docs

changelog.d/4666.feature

-Allow registration to be handled by a worker instance.
+Allow registration and login to be handled by a worker instance.

docs/workers.rst

@@ -222,11 +222,12 @@ following regular expressions::
     ^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/context/.*$
     ^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/members$
     ^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/state$
+    ^/_matrix/client/(api/v1|r0|unstable)/login$
 
 Additionally, the following REST endpoints can be handled, but all requests must
 be routed to the same instance::
 
-    ^/_matrix/client/(api/v1|r0|unstable)/register$
+    ^/_matrix/client/(r0|unstable)/register$
 
 
 ``synapse.app.user_dir``