doc: add ChALkeR as collaborator

Using the non-transliterated name as requested.

The transliteration is "Nikita Skovoroda" (first and last name),
if anyone will want to organize non-ASCII names.

PR-URL: https://github.com/nodejs/io.js/pull/1927


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Johan Bergström <bugs@bergstroem.nu>
Reviewed-By: Chris Dickinson <christopher.s.dickinson@gmail.com>