updata norm doc

* add distributed dir and doc

* remove start_processes & move DataParallel

* add get rank and world size

* add cn docs

* add index to distributed_cn

* add white list api

* add api white list

* add cn to api name

* polish details

* add rst suffix

* add py function

* Add the argmax, argmin api doc for the api 2.0, test=develop

* test distribution doc

* add paddle.rst

* fix paddle.rst

* Add distribution_cn

* Fixed doc in cn

* fix cn doc

* test paddle_cn

* Distributin, temp fix of Normal and Uniform

* fix code doc

* test_broadcast

* optimize doc

* return to the original index_cn.rst

* hidden _to_variable func

* Add the max, min, maximum, minimum api for the paddle 2.0

update the api doc for the cumsum op 

 Fix the compare ops doc for the api2.0

Fix the argsort, sort the api doc for paddle2.0