add readme for demo

python/examples/deeplabv3/README_CN.md

-# i图像分割
+# 图像分割
 
 ## 获取模型
 

python/examples/mobilenet/README.md

+# Image Classification
+
+## Get Model
+
+```
+python -m paddle_serving_app.package --get_model mobilenet_v2_imagenet
+tar -xzvf mobilenet_v2_imagenet.tar.gz
+```
+
+## RPC Service
+
+### Start Service
+
+```
+python -m paddle_serving_server_gpu.serve --model mobilenet_v2_imagenet_model --gpu_ids 0 --port 9393
+```
+
+### Client Prediction
+
+```
+python mobilenet_tutorial.py
+```

python/examples/mobilenet/README_CN.md

+# 图像分类
+
+## 获取模型
+
+```
+python -m paddle_serving_app.package --get_model mobilenet_v2_imagenet
+tar -xzvf mobilenet_v2_imagenet.tar.gz
+```
+
+## RPC 服务
+
+### 启动服务端
+
+```
+python -m paddle_serving_server_gpu.serve --model mobilenet_v2_imagenet_model --gpu_ids 0 --port 9393
+```
+
+### 客户端预测
+
+```
+python mobilenet_tutorial.py
+```

python/examples/resnet_v2_50/README.md

+# Image Classification
+
+## Get Model
+
+```
+python -m paddle_serving_app.package --get_model resnet_v2_50_imagenet
+tar -xzvf resnet_v2_50_imagenet.tar.gz
+```
+
+## RPC Service
+
+### Start Service
+
+```
+python -m paddle_serving_server_gpu.serve --model resnet_v2_50_imagenet_model --gpu_ids 0 --port 9393
+```
+
+### Client Prediction
+
+```
+python resnet50_v2_tutorial.py
+```

python/examples/resnet_v2_50/README_CN.md

+# 图像分类
+
+## 获取模型
+
+```
+python -m paddle_serving_app.package --get_model resnet_v2_50_imagenet
+tar -xzvf resnet_v2_50_imagenet.tar.gz
+```
+
+## RPC 服务
+
+### 启动服务端
+
+```
+python -m paddle_serving_server_gpu.serve --model resnet_v2_50_imagenet_model --gpu_ids 0 --port 9393
+```
+
+### 客户端预测
+
+```
+python resnet50_v2_tutorial.py
+```

python/examples/unet_for_image_seg/README.md

+# Image Segmentation
+
+## Get Model
+
+```
+python -m paddle_serving_app.package --get_model unet
+tar -xzvf unet.tar.gz
+```
+
+## RPC Service
+
+### Start Service
+
+```
+python -m paddle_serving_server_gpu.serve --model unet_model --gpu_ids 0 --port 9494
+```
+
+### Client Prediction
+
+```
+python seg_client.py
+```

python/examples/unet_for_image_seg/README_CN.md

+# 图像分割
+
+## 获取模型
+
+```
+python -m paddle_serving_app.package --get_model unet
+tar -xzvf unet.tar.gz
+```
+
+## RPC 服务
+
+### 启动服务端
+
+```
+python -m paddle_serving_server_gpu.serve --model unet_model --gpu_ids 0 --port 9494
+```
+
+### 客户端预测
+
+```
+python seg_client.py
+```