Fix the doc examples for those apis

* modify the doc, test=develop

test=develop

* support LoDTensorArray

* fix comma

* add example of LoDTensorArray

* fix typo

* rewrite the sigmoid_focal_loss code example. test=develop

* fix spelling mistake in comments of code example.test=develop

test=develop

* fix sample code diff for OP(retinanet_detection_output, retinanet_target_assign), fix  default value for OP(sigmoid_focal_loss). test=develop

* fix float value. test=develop

* add int type for gamma and alpha of sigmoid_focal_loss.test=develop

fix Chinese doc bug in argsort, add the dtype support of dtypes

fix sample code diff for OP(retinanet_detection_output, retinanet_target_assign), fix `gamma` default value for OP(sigmoid_focal_loss) (#1971)

* fix sample code diff for OP(retinanet_detection_output, retinanet_target_assign), fix  default value for OP(sigmoid_focal_loss). test=develop

* fix float value. test=develop

Refine the doc of create_global_var, pad, pad_constant_like and pad2d to make it consistent with en doc.

* add inplace_abn. test=develop

* fix lstm doc error

* fix lstm doc error

* remove unused line in lstm doc

* Add learning_rate in NoamDecay test=develop

* Update sample code test=develop

* add update for gelu: approximation option

* removefill_constant_batch_size_like  gaussian_random_batch_size_like  uniform_random_batch_size_like_cn API doc test=develop

* add filter_by_instag out_val_ifempty cn api test=develop

* change out_val_ifempty to out_val_if_empty in filter_by_instag test=develop

In elementwise_min api doc has the error, all the api just use the elementwise_max op, we just correct the doc.

Fix the pow doc bug, change the pow parameter from 2.0 to 3.0

Fix the compare op force_cpu params  bug