* add unique doc

* 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

* modify the doc, test=develop

* 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

* Update `paddle.add` docs

remove `out` and `alpha`
explain broadcast semantics
update doc samples

* Apply template and fix alias

* Update `no_grad` docs

add alias `paddle.no_grad`
use `paddle.no_grad()` for decorator usage
update code sample

* Fix alias

* Reword decorator usage note

* 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