update README

python/examples/pipeline/grpc-gateway/README_CN.md

@@ -57,8 +57,8 @@ go build proxy_server.go
 ```shell
 cd ../imdb_model_ensemble/
 sh get_data.sh
-python -m paddle_serving_server_gpu.serve --model imdb_cnn_model --port 9292 &> cnn.log &
-python -m paddle_serving_server_gpu.serve --model imdb_bow_model --port 9393 &> bow.log &
+python -m paddle_serving_server.serve --model imdb_cnn_model --port 9292 &> cnn.log &
+python -m paddle_serving_server.serve --model imdb_bow_model --port 9393 &> bow.log &
 python test_pipeline_server.py &> pipeline.log &
 cd -
 ./proxy_server &> gateway.log &