docs: add supported locale list to readme

[thatlittleboy]

Fixes #9

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Logs:

• I just ran Google translate on the various text in grammar.js, please let me know if the list of languages I've compiled is inaccurate.

[gbprod]

Thanks for that!

Can you check if it matchs with git supported languages (https://github.com/git/git/tree/master/po) ans order languages alphabetically ?

[thatlittleboy]

Yep will do :) Will push the updates up soon

[thatlittleboy]

I took reference from the "Please enter the commit message ..." line, and compared it against git's supported locales (the link u shared).

Currently, I think we're missing:

• bg (Bulgarian)
• is (Icelandic)

It is possible that the other languages are not completely supported in our grammar.js as well, since I only based it on this one line. But this should be good enough for now.

I also took the liberty to sort the translations inside grammar.js to this particular README order (i.e., alphabetical, except for English at the top) for this one line. I think it makes it easier to keep track of whether a particular line's translation is supported or not, but if you want me to revert this change, I can do so.

[gbprod]

Icelandic is empty and it seems that I've missed some Bulgarian translations 😅 , I create an issue

[gbprod]

Can you add a link to https://github.com/git/git/tree/master/po in the README ?

Thanks

[thatlittleboy]

Done!

[gbprod]

Thanks!