[translations] Doc-ja: add cheatsheet.itely to NR.

[Yoshiki Sawada <sawada.yoshiki@xxxxxxxxx>]

Hi all,

I've forgot to do "git add cheatsheet.itely" before making
the previous patch.
So that, I send another patch to add cheatsheet.itely to NR.
Please, apply it :)

Thanks,
Yoshiki Sawada (Japan)