Merge pull request #1863 from Tony133/docs/grpc-improvement

docs(grpc): improvement

Author: kamilmysliwiec

content/microservices/grpc.md

@@ -411,7 +411,11 @@ bidiHello(messages: Observable<any>, metadata: Metadata, call: ServerDuplexStrea
     });
   };
   const onComplete = () => subject.complete();
-  messages.subscribe(onNext, null, onComplete);
+  messages.subscribe({
+    next: onNext,
+    complete: onComplete,
+  });
+
 
   return subject.asObservable();
 }