Move simplified Chinese translations to correct directory

[Mygod]

No description provided.

[dschuermann]

Hey thanks for the contribution.
Can you explain the difference between zh and zh-CN?
The translations are managed on Transifex, so if we want to change that, we must do it here: https://www.transifex.com/privacyapps/donations/languages/

[Mygod]

According to this, putting translations there should be fine as well if this was a client app. But complications arises when developers use this library with resConfigs to trim out unwanted resources. All string resources are provided as zh-rCN in support libraries. Luckily in recent versions, Android allows users to specify secondary languages. I believe everything should be fine as long as you use zh-rCN just like AOSP does.