Remove not used images
Created by: shanyi15
According to comment in https://github.com/PaddlePaddle/Paddle/pull/9104,
please remove this four
in https://github.com/PaddlePaddle/Paddle/tree/develop/doc/design/images
thanks
Created by: shanyi15
According to comment in https://github.com/PaddlePaddle/Paddle/pull/9104,
please remove this four
in https://github.com/PaddlePaddle/Paddle/tree/develop/doc/design/images
thanks