Add Chinese Translation Team
Merge remote-tracking branch 'chinesization/master'
Fix html markdown for span class="not-set" when time is not set

See #4000
Update _item.php
Merge pull request #4002 from abajja/Translation-Review-README.md

Translation review readme.md
Merge pull request #4001 from SDKiller/patch-2

Fix html markdown for span class="not-set" when time is not set
Update intro-upgrade-from-v1.md

I think it is a small mistake.
English guide typo [skip ci]
Merge pull request #4007 from qiansen1386/patch-7

guide mistake: suppose to be "role", not "name" I think.
Merge pull request #4008 from lucianobaraglia/translation-es

English guide typo [skip ci]
Update README [skip ci]
transalating intro-upgrade-from-v1, left with asset, query builder, form, etc.
Spanish guide structure-controllers.md [skip ci]
Same fix as ff8225c78d23d04731e98eebbd57c48b59e493eb [skip ci]
Finished widget tutorial [skip ci]
Update translation-status.md
Merge pull request #4011 from lucianobaraglia/translation-es

Spanish guide structure-controllers.md [skip ci]
Minor changes in Estonian translation
Merge pull request #4014 from stevekr/master

Minor changes in Estonian translation
更新文档