[Cocos2d-JS] Improve change log and upgrade guide
Merge branch 'master' of https://github.com/cocos2d/cocos-docs
[Cocos2d-JS] Finish chinese upgrade guide for 3.0 rc0
Merge branch 'master' of https://github.com/cocos2d/cocos-docs
Merge pull request #382 from pandamicro/master

[Cocos2d-JS] Improve change log and upgrade guide