Created by: lcy-seso

I find there is no documentation on how to write a user-defined reader to read users' data.

Currently, PaddleBook and Paddle/demos are the only officially guide on how to use V2 API. In these examples, the process of feeding raw data to PaddlePaddle are encapsulated, and there is no documentation about how to write a user-defined reader as we previously provided:

• http://deeplearning.baidu.com/doc/deprecated_doc/doc/ui/data_provider/pydataprovider2.html

Though the interface does not change in essence, a documentation about how to create a user-defined reader is still needed.