fix links and format [skip ci]
fix wrong file name [skip ci]
Guide-zh-CN intro-yii.md proofread.
Guide-zh-CN intro-upgrade-from-v1.md proofread.
Merge pull request #5 from AbrahamGreyson/master

proofread intro-yii.md and intro-upgrade-from-v1.md
proofreading [skip ci]
proofreading [skip ci]
proofreading [skip ci]
minor fix [skip ci]
translate concept-aliases and autoloading [skip cii]
Guide-zh-CN intro-upgrade-from-v1.md proofread.
Merge pull request #6 from AbrahamGreyson/master

Guide-zh-CN intro-upgrade-from-v1.md proofread.
Guide-zh-cn/start-installation.md proofread.
Merge pull request #7 from AbrahamGreyson/master

Guide-zh-cn/start-installation.md proofread.
improved description to deliver the original concepts better. [skip ci]
translated concept-autoloading.md [skip ci]
Merge pull request #4169 from yii2-chinesization/master

New Chinese translations are ready to serve