Update design doc based on early implementation
Update design doc based on early implementation

luotao1/Paddle,pkuyym/Paddle,pkuyym/Paddle,jacquesqiao/Paddle,reyoung/Paddle,luotao1/Paddle,Canpio/Paddle,pkuyym/Paddle,QiJune/Paddle,tensor-tang/Paddle,putcn/Paddle,chengduoZH/Paddle,baidu/Paddle,QiJune/Paddle,reyoung/Paddle,jacquesqiao/Paddle,PaddlePaddle/Paddle,Canpio/Paddle,baidu/Paddle,Canpio/Paddle,baidu/Paddle,reyoung/Paddle,chengduoZH/Paddle,chengduoZH/Paddle,putcn/Paddle,PaddlePaddle/Paddle,putcn/Paddle,luotao1/Paddle,Canpio/Paddle,Canpio/Paddle,PaddlePaddle/Paddle,PaddlePaddle/Paddle,Canpio/Paddle,reyoung/Paddle,pkuyym/Paddle,QiJune/Paddle,jacquesqiao/Paddle,QiJune/Paddle,chengduoZH/Paddle,reyoung/Paddle,PaddlePaddle/Paddle,luotao1/Paddle,putcn/Paddle,QiJune/Paddle,tensor-tang/Paddle,Canpio/Paddle,jacquesqiao/Paddle,luotao1/Paddle,reyoung/Paddle,tensor-tang/Paddle,tensor-tang/Paddle,pkuyym/Paddle,luotao1/Paddle,QiJune/Paddle,baidu/Paddle,Canpio/Paddle,PaddlePaddle/Paddle,putcn/Paddle,luotao1/Paddle,tensor-tang/Paddle,putcn/Paddle,chengduoZH/Paddle,jacquesqiao/Paddle,baidu/Paddle,pkuyym/Paddle,jacquesqiao/Paddle,PaddlePaddle/Paddle