Asynchronous-API tutorial issue

[NazaretRJ]

On the part of the Async Server code. It is not clear what function it is used. The part is: ServerContext context; HelloRequest request; ServerAsyncResponseWriter<HelloReply> responder; service.RequestSayHello(&context, &request, &responder, &cq, &cq, (void*)1);

If I search for the HelloRequest request; It is not found on the greater_async_server.cc

I think the code has changed and the documentation is out of date. Please take a look.

[easwars]

@veblush @temawi Could you please check if our docs are out of date?

I'm not sure who the owner is for this tutorial: https://grpc.io/docs/languages/cpp/async/