doc: add robertkowalski as collaborator
doc: add robertkowalski as collaborator

PR-URL: https://github.com/iojs/io.js/pull/977
Reviewed-By: Evan Lucas <ad0310dc5270cefb6ee6879263270aed9b1e9982@me.com>
Reviewed-By: Christian Tellnes <2314b2e3a4a1f7db165be2aafbf1efd78f28cc97@tellnes.com>
Reviewed-By: Rod Vagg <4dc7c9ec434ed06502767136789763ec11d2c4b7@va.gg>

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