* proofread & update zh-CN setting form locale

* Pull in new devise zh-CN translations from their wiki

https://github.com/plataformatec/devise/wiki/I18n,
more precisely https://gist.github.com/Artoria2e5/6d2a06ca9e92a417afc627b5000f4690

* pull in zh-CN translation for doorkeeper

... from https://github.com/doorkeeper-gem/doorkeeper-i18n/pull/31/