Add Chinese translations

[qftgtr]

The Chinese translation for talkyard.

[kajmagnus]

Hi Zehao @qftgtr,

Ok so I've recently added even more translation values. I'm thinking maybe it'd be annoying for you, to keep up with the textual changes I'm doing every now and then? (I mean, you'd need to submit new PRs every now and then, to update the Chinese translations.)

What about this: If you squash the commits, and sign the CLA (by editing the commit message), then, some time later I can merge the PR, and then I can find a freelancer at e.g. Upwork, who speaks Chinese, and does the small remaining and re-occurring work, with updating the Chinese translation, whenever I change text messages and button titles?

(Probably the Chinese translation, and all other translations, from time to time will be a bit out of date. It'd take a while, after I change some texts / button titles, until I had time to contact the translator(s). )

[kajmagnus]

Hi again Phil, @qftgtr , what if you type here that you agree to the CLA? I.e. this file:
https://github.com/debiki/talkyard/blob/master/docs/CLA-v2.txt

Then I can include this Chinese translation in Talkyard.

Sorry I didn't think of a more light weight approach for agreeing to the CLA and adding new translations before.