* 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

* test=document_preview

* 0823 update FluidDoc,test=document_preview

* add two files

* ok

* ok

* ok

* add check_approval

* check approval

* check approval

* check approval

* check approval

* check approval

* check approval

* add check_approval

* add check_approval

* add check_approval

* add check_approval

* add check_approval

* change api

* change api