fix typo in anchor. fixes
@@ -63,7 +63,7 @@ If the client sends messages to users on remote domains, those messages should
be sent on to the remote servers via
`federation`_.
-.. _`federation`: ../server_server/latest.html#send-to-device-messages
+.. _`federation`: ../server_server/latest.html#send-to-device-messaging
.. TODO-spec:
