docs: fixed create_ws_route_handlers typo. (#3618)

Co-authored-by: Alc-Alc <45509143+Alc-Alc@users.noreply.github.com>

docs/usage/channels.rst

@@ -438,7 +438,7 @@ route handlers.
 
 .. literalinclude:: /examples/channels/create_route_handlers.py
     :language: python
-    :caption: Setting ``create_route_handlers=True`` will create route handlers for all ``channels``
+    :caption: Setting ``create_ws_route_handlers=True`` will create route handlers for all ``channels``