Correct Belarusian language support indictions

> > Hey guys, Encode Sans is now ready in @googlefonts Go get it!
>
> Thank you for your work. Bit of mistake in description(s): seeing Belarusian in supported languages, I expected Cyrillics, but actually it meant 'Latin Belarusian', which in the real world is a non-entity (real world != Wikipedia Universe). Same for the Libre and Encode families.

- https://twitter.com/georgius700/status/942278387095298048

A few places to check for and fix this:

- [ ] in descriptions
- [ ] in language checking web tool from graphicore
- [ ] in language checking web tool from impallari
- [ ] in language checking web tool internal