Translate:

• all files in _data/lang/ru/
• all files in _i18n/ru/

Edit:

• add "ru" tag in _config.yml
• add "ru" tag in _i18n/ (ar.yml, en.yml, es.yml, fr.yml, it.yml, pl.yml)

Moneropedia:

• сompletely tested to 100%
• all hyperlinks and footnotes to the notes work correctly

Calling to review: @erciccione @Monerorus(GitHub) @LvMsterfild(GitHub) @AJIekceu4(GitHub) @TheFuzzStone