modify cls and instseg docs (PaddlePaddle#1903)

Merge pull request PaddlePaddle#1774 from cuicheng01/develop

update docs

Merge pull request PaddlePaddle#1119 from FlyingQianMM/develop_qh

add CHANGELOG for release2.0

Merge pull request PaddlePaddle#760 from FlyingQianMM/release/2.0-rc_qh

set version to 2.0.0rc0

merge from deploykit (PaddlePaddle#754)

* merge from deploykit

* del DS_Store file

Delete .DS_Store

update version

Merge pull request PaddlePaddle#218 from joey12300/develop

encapsulate GenerateColormap in Visualize

update change log

delete useless files