Polish elementwise_add/sub/mul/div documents

* fix api, test=develop, test=document_preview

* Refine stack op api doc

test=develop
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* refine stack api
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* add strided_slice op cn doc test=develop

* fix typo test=develop

* fix typo test=develop

* fix typo test=develop

* fix typo test=develop

* fix typo test=develop

* fix typo test=develop

* fix according review  test=develop

* fix according review  test=develop

* fix according review  test=develop

* add LookaheadOptimizer_cn.rst
test=document_preview

* modify LookaheadOptimizer_cn.rst, test=document_fix

* modify LookaheadOptimizer_cn.rst, test=document_fix

* modify LookaheadOptimizer_cn.rst, test=document_fix

remove reader.compose,reader.creator.text_file,reader.creator.np_array,reader.creator.recordio ,because these inferences are removed in develop (#1307)

* refine doc

* follow lanxiang's comments, test=develop

* fix api_cn of 11 APIs
test=develop
test=document_preview

* fix format of math and params

* fix tensor dimension description

* modify less_than api

* modify leaky_relu api

* modify log api

* modify logical_and api

* modify logical_or api

* modify logical_not api

* modify logical_xor api

* add param_attr example

* move example

* refine code emxpale

* Refine create_array op api doc.

test=develop
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* Refine create_array api doc

test=develop
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* update DistributeTranspilerConfig_cn, test=develop

* Rewrite firstn and shuffle functions, test=develop

* Rewrite firstn and shuffle functions, test=develop

* update, test=develop

* updata, test=develop

* update reader.shuffle and reader.firstn, test=develop

* update cn doc for assign op

* refine the description of assign op

* fix scope doc

* Polish executor doc

* update the cn_doc of double_buffer

* add more information for double_buffer api

* add optional for parameters have default value

* add more infomation for Variable Reader

* correct the expression

* update the mul cn_api doc

* add optional for parameters have default value

* fix gather_nd scatter_nd_add scatter_nd, test=develop

* fix centerloss, test=develop

* fix the description, test=develop

* fix the doc, test=develop

* expose set_gradient_clip, test=develop

* follow lanxiang's comments, test=develop

* update the has_inf cn_api doc

* alter tensor/LoDtensor to Tensor/LoDTensor

* add reference link of elementwise_pow. test=document_preview

* fix Chinese doc of four API. test=develop, test=document_preview

* fix optional argument.  test=develop, test=document_preview

* fix cn doc accoring to reviews. test=develop, test=document_preview

update the has_nan cn_api doc

alter tensor LoDtensor to Tensor LoDTensor

update cumsum api doc

add Tensor/lodTensor for input x description

alter the optional for parameters have default value

test=develop
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* fix argsort doc
test=document_preview

* fix
test=document_preview

* test=document_preview

* fix
test=document_preview

* fix
test=document_preview

* fix argmax doc
test=document_preview

* fix
test=document_preview

test=develop
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* modify L1DecayRegularizer, L1Decay, L2DecayRegularizer and L2Decay, test=develop

* update cn doc for ones and zeros op

* fix the types of shape in zeros op

* add return type for ones and zeros op

* list all supported data types for zeros and ones op