Document that connect() drivers must pass the transport's context builder

The JSON-response-mode refusal of request-scoped server requests takes
effect through the dispatcher's transport_builder, so a caller driving
the transport's streams by hand needs to pass transport_context_for
the way the session manager does.

No-Verification-Needed: docstring-only edit

Author: maxisbey

src/mcp/server/streamable_http.py

@@ -964,6 +964,12 @@ async def connect(
     ]:
         """Context manager that provides read and write streams for a connection.
 
+        Drive the yielded streams through a `JSONRPCDispatcher` built with
+        `transport_context_for` as its `transport_builder`, as the session
+        manager does: that is what makes the request-scoped channel refuse
+        server-initiated requests in JSON-response mode instead of parking
+        them where nothing can deliver them.
+
         Yields:
             Tuple of (read_stream, write_stream) for bidirectional communication
         """