doc: update client interceptors chaining example with grpc functions (#…

…669)

Replace middleware.ChainXXXClient(...) functions with
grpc.WithChainXXXInterceptor(...).

Also fix the number of parenthesis in the server interceptors chaining
example.

doc.go

@@ -21,7 +21,7 @@ Simple way of turning a multiple interceptors into a single interceptor. Here's
 server chaining:
 
  myServer := grpc.NewServer(
- grpc.ChainStreamInterceptor(loggingStream, monitoringStream, authStream)),
+ grpc.ChainStreamInterceptor(loggingStream, monitoringStream, authStream),
  grpc.ChainUnaryInterceptor(loggingUnary, monitoringUnary, authUnary),
  )
 
@@ -31,8 +31,8 @@ Here's an example for client side chaining:
 
  clientConn, err = grpc.Dial(
  address,
- grpc.WithUnaryInterceptor(middleware.ChainUnaryClient(monitoringClientUnary, retryUnary)),
- grpc.WithStreamInterceptor(middleware.ChainStreamClient(monitoringClientStream, retryStream)),
+ grpc.WithChainUnaryInterceptor(monitoringClientUnary, retryUnary),
+ grpc.WithChainStreamInterceptor(monitoringClientStream, retryStream),
  )
  client = testpb.NewTestServiceClient(clientConn)
  resp, err := client.PingEmpty(s.ctx, &myservice.Request{Msg: "hello"})