Correct display name for `zh_CN` (de facto alias of `zh-Hans`)
Hello,
It has long been common practice in the software industry to use zh-CN to represent zh-Hans and use zh-TW to represent zh-Hant (more specifically zh-Hant-TW).
They are both used in the VideoLan projects too.
This commit only corrects the name for zh-CN.
Since we don't have a zh-HK team yet, it's currently too arbitrary to modify the zh-TW name.