docs: remove stale header guidance for AppendRows

PiperOrigin-RevId: 485941276

google/cloud/bigquery/storage/v1/storage.proto

@@ -167,13 +167,6 @@ service BigQueryWrite {
   // * For PENDING streams, data is not made visible until the stream itself is
   // finalized (via the `FinalizeWriteStream` rpc), and the stream is explicitly
   // committed via the `BatchCommitWriteStreams` rpc.
-  //
-  // Note: For users coding against the gRPC api directly, it may be
-  // necessary to supply the x-goog-request-params system parameter
-  // with `write_stream=<full_write_stream_name>`.
-  //
-  // More information about system parameters:
-  // https://cloud.google.com/apis/docs/system-parameters
   rpc AppendRows(stream AppendRowsRequest) returns (stream AppendRowsResponse) {
     option (google.api.http) = {
       post: "/v1/{write_stream=projects/*/datasets/*/tables/*/streams/*}"