updated docs
Merge pull request #498 from pandamicro/master

[Cocos2d-JS] Update doc references
Merge pull request #496 from gloryming/master

updated docs
[Cocos2d-JS] Improve docs for 3.0 Release
Merge branches 'master' and 'master' of https://github.com/cocos2d/cocos-docs
[Cocos2d-JS] Improve docs for 3.0 Release