* modified README and demo

* Update qat.rst

* Update quantization_api.rst

* Update quant_post_static_tutorial_en.md

* Update quant_aware_tutorial_en.md

* Update quant_aware_training_tutorial.md

* Update quant_aware_tutorial.md

* Update dygraph_quant_post_tutorial.md

* Update quant_post_static_tutorial_en.md

* Update quant_aware_tutorial_en.md

* Update quant_aware_training_tutorial.md