Added translation into Russian

[Ser-Bul]

Hi guys, please review and let me know if you find any problems with the suggested addition.

[Jean-BaptisteC]

Thanks for your contribution, automatic selector language is very useful
Can you fix errors?

[Ser-Bul]

Thanks for your contribution, automatic selector language is very useful Can you fix errors?

Fixed.

[Jean-BaptisteC]

How it's works if pages is missing in russian or french.
Selector shown english page?

[Ser-Bul]

checking...

[Ser-Bul]

It just returns standard error 404.
Though it behaves so even without the 'alias.html', so it seems like something should be reconfigured in Hugo to make it fallback to English pages. But I couldn't figure out what exactly.

[pnu-s]

Hello there!

We'll need to discuss internally whether we want/need to translate the website into more languages than French and English. We are adding this to our next agenda and we'll let you know!

[Jean-BaptisteC]

Is it possible to separate changes about the detection of user language in another PR?