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

* add uniform op doc

* fix uniform en format

* delete useless code

* 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

* refine sign tanh api, test=develop

* Add Tanh, test=develop

* fix en, test=develop

* test=develop, add addmm doc

* add addmm doc

* test=develop, add addmm doc

* test=develop, add pad doc

* restore addmm

* test=develop, add pad

* test=develop, fix pad interface

* test=develop, add pad eng doc link

* test=develop, add other pads

* test=develop, remove pad default

* test=develop, fix const pad1d code

* test=develop, fix var

* test=develop, fix pad typo

* test=develop, rename tovar to totensor

* test=develop, fix code

* test=develop, fix typo

* test=develop, fix cos_sim interface

* test=develop, fix typo

* modify the doc, test=develop

* refine bceloss doc

* fix doc

* fix name

* fix api 2.0 directory migration

* add dir file and change x to input

* add doc of loss function binary_cross_entropy.

* delete static demo code.

* Update `paddle.clamp` doc

rename to `paddle.clip`
`input` -> `x`
remove `out`
update samples
wording: `Variable` - > `Tensor`

* Apply template

* Update `enable_imperative` -> `disable_static`

* Update sample: `to_tensor`

* modify the doc, test=develop

* add 2/3d adaptive_pooling

* fix format

* fix format

* add en doc rst

* fix format

* fix doc

* fix doc

* refine example code

* unify example code

* Udpate the doc format for the paddle, test=develop

* modify nn.data into static.data

* Update index_cn.rst

* nn.data to static.data

* remove alias

* rename the inputs and update code example, test=develop

* update doc

* polish some docs

* polish some docs

* Update square_cn.rst

* polish some docs

* polish some docs

* polish round docs

* polish round docs

* Update square_cn.rst

* polish some docs

* polish functional_cn.rst

* add DataParallel cn doc

* polish details

* fix method declarative error

* polish format

* fix sample code error

* append to white list

* polish some docs

* polish some docs

* Update square_cn.rst

* polish some docs

* polish some docs

* polish round docs

* polish round docs

* Update square_cn.rst

* remove the out args

* polish sqrt doc

* Update sqrt_cn.rst

* Update sqrt_cn.rst

* Update sqrt_cn.rst

* Add Chinese documents for api paddle.fluid.dygraph.enabled, test=develop, test=document_fix

* Add Chinese documents for api paddle.fluid.dygraph.enabled 2, test=develop, test=document_fix

* Add Chinese documents for api paddle.fluid.dygraph.enabled 3, test=develop, test=document_fix

* Add Chinese documents for api paddle.fluid.dygraph.enabled 4, test=develop, test=document_fix