Add mn-MN translation

Hey Wojciech,

First of all, thanks for making this awesome diagram. And here is a small contribution for it. It's not perfect but I think it's good start for Mongolian translation.

Cheers.

Thanks! Think you can find someone else speaking Mongolian to have a look if you are unsure? :)

Hi @wojtekmaj,

Absolutely,

hey @dulmandakh whenever you have a spare time - can you please take a look my translation here? Thank you! 🙏

@tengis Are you willing to resolve conflicts & fix the issues we've discussed or should I close this PR?