Add Chinese Translation Team
Merge remote-tracking branch 'chinesization/master'
Update README [skip ci]
transalating intro-upgrade-from-v1, left with asset, query builder, form, etc.
更新文档
Translated intro-upgrade-from-v1 [skip ci]
Merge pull request #4029 from yii2-chinesization/master

add translation for intro-upgrade-from-v1 [skip ci]