Update contribute.md
Update contribute.md

io.js isn't really a thing anymore, and generators are enabled by default.
HBOCodeLabs/bluebird,petkaantonov/bluebird,petkaantonov/bluebird,HBOCodeLabs/bluebird,BridgeAR/bluebird,justsml/bluebird,BridgeAR/bluebird,BridgeAR/bluebird,petkaantonov/bluebird,yonjah/bluebird,justsml/bluebird,yonjah/bluebird,justsml/bluebird,HBOCodeLabs/bluebird,yonjah/bluebird