Add missing user_dir endpoint from the generic worker documentation

changelog.d/12773.doc

@@ -0,0 +1 @@
+Add missing user directory endpoint from the generic worker documentation. Contributed by @olmari.

docs/workers.md

@@ -251,6 +251,8 @@ information.
     # Presence requests
     ^/_matrix/client/(api/v1|r0|v3|unstable)/presence/
 
+    # User directory queries
+    ^/_matrix/client/(r0|v3|unstable)/user_directory/search$
 
 Additionally, the following REST endpoints can be handled for GET requests:
 
@@ -445,6 +447,10 @@ Specify its name in the shared configuration as follows:
 update_user_directory_from_worker: worker_name
 ```
 
+It can handle REST endpoint matching the following regular expression:
+
+    ^/_matrix/client/(r0|v3|unstable)/user_directory/search$
+
 This work cannot be load-balanced; please ensure the main process is restarted
 after setting this option in the shared configuration!