Review of wording

src/compiler/python_generator.cc

@@ -778,7 +778,8 @@ pair<bool, grpc::string> PrivateGenerator::GetGrpcServices() {
       out->Print(
           "# Generated by the gRPC Python protocol compiler plugin. "
           "DO NOT EDIT!\n\"\"\""
-          "Protocol buffer generated client and server classes.\"\"\"\n");
+          "Client and server classes corresponding to protobuf-defined services."
+          "\"\"\"\n");
       if (!PrintPreamble(out.get())) {
         return make_pair(false, "");
       }