doc: add petkaantonov as collaborator
doc: add petkaantonov as collaborator

PR-URL: https://github.com/iojs/io.js/pull/1179
Reviewed-By: Ben Noordhuis <59bd0a3ff43b32849b319e645d4798d8a5d1e889@bnoordhuis.nl>
Reviewed-By: cjihrig <838f779c91673db29b8572ea3f54d191d3878ae2@gmail.com>

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node