update Chinese guide.
update Chinese guide.
update start-installation.md Chinese version.
proofread start-hello.md Chinese version.
proofread start-forms.md Chinese version.
proofread start-databases.md Chinese version.
sync images to Chinese version guide.
update start-gii.md Chinese version.
update start-looking-ahead.md Chinese version.
Merge branch 'master' of github.com:yii2-chinesization/yii2
update structure-overview.md Chinese version.