* Update README.md

Polish README
Co-authored-by: NZeyu Chen <chenzeyu01@baidu.com>
Co-authored-by: NSteffy-zxf <48793257+Steffy-zxf@users.noreply.github.com>

* uniform file name convention

* update version

* update docs

* update docs

* update demo

* simplify img cls demo

* remove elmo demo

* simplify multi-label cls demo

* simplify multi-label cls demo

* simplify img cls demo

* simplify text cls demo

* simplify lac demo

* simplify ssd demo

* simplify qa cls demo

* simplify regression demo

* simplify reading comprehension demo

* simplify sequence labeling demo

* simplify senta demo

* Modify the coding format of senta_demo.py and lac_demo.py

* Add the toxic dataset and multi-label task

* Add the multi_label classification demo

* Update teh demo text-cls and seq-label

* Fix the encoding format