* 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

* 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

* 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

* Update `paddle.add` docs

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

* Apply template and fix alias

* remove the out args

* update log docs

* update log1p docs

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

update the api doc for the cumsum op 

update the sort api, delete the unused index output

 Fix the compare ops doc for the api2.0

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

* add cholesky_cn

* add dot, inverse, test=document

* fix doc, test=document

* fix doc, test=document

fix cross op doc for API2.0

Add new operator api: paddle.histc(input, bins=100, min=0, max=0)