message: fix doc style for ocr
diff: @@ -19,6 +19,7 @@ tar xf test_imgs.tar
  ### Start Service
  Select a startup mode according to CPU / GPU device
  +
  After the -- model parameter, the folder path of multiple model files is passed in to start the prediction service of multiple model concatenation.
  ```
  #for cpu user
  @@ -28,8 +29,10 @@ python -m paddle_serving_server_gpu.serve --model ocr_det_model ocr_rec_model --
  ```
  ### Client Prediction
  -The pre-processing and post-processing is in the C + + server part, the image's Base64 encoded string is passed into the C + + server
  +The pre-processing and post-processing is in the C + + server part, the image's Base64 encoded string is passed into the C + + server.
  +
  so the value of parameter `feed_var` which is in the file `ocr_det_client/serving_client_conf.prototxt` should be changed.
  +
  for this case, `feed_type` should be 3(which means the data type is string),`shape` should be 1.
  By passing in multiple client folder paths, the client can be started for multi model prediction.
  