* add an example for gan training

* remove data element

* fix as comments

* add type_as

* fix as comment

* refine

* fix as comment

* add more descriptions

* fix as comment

* fix a api

* Add the distributed training script

* fix md format

* [Docs] cross library import examples.

* update

* resolve comments

* [Docs] Add resume training examples

* refine

* rename filename

* minor refinement

* fix comments

* resolve comments

* resolve comments

* [Docs] Add speed training examples

* refine

* refine

* rename filename

* minor refine

* Add save_gpu_memory docs

* update

* fix comment

* fix comment