fix readme

python/examples/imagenet/README.md

@@ -8,6 +8,13 @@ The example uses the ResNet50_vd model to perform the imagenet 1000 classificati
 ```
 sh get_model.sh
 ```
+
+### Install preprocess module
+
+```
+pip install paddle_serving_app
+```
+
 ### HTTP Infer
 
 launch server side

python/examples/imagenet/README_CN.md

@@ -8,6 +8,13 @@
 ```
 sh get_model.sh
 ```
+
+### 安装数据预处理模块
+
+```
+pip install paddle_serving_app
+```
+
 ### 执行HTTP预测服务
 
 启动server端

python/examples/senta/README.md

@@ -4,6 +4,12 @@
 ```
 sh get_data.sh
 ```
+## Install preprocess module
+
+```
+pip install paddle_serving_app
+```
+
 ## Start http service
 ```
 python senta_web_service.py senta_bilstm_model/ workdir 9292

python/examples/senta/README_CN.md

@@ -4,6 +4,11 @@
 ```
 sh get_data.sh
 ```
+## 安装数据预处理模块
+```
+pip install paddle_serving_app
+```
+
 ## 启动HTTP服务
 ```
 python senta_web_service.py senta_bilstm_model/ workdir 9292