doc: add monsanto as collaborator

PR-URL: #1932
Reviewed-By: Johan Bergström <bugs@bergstroem.nu>

Author: monsanto

README.md

@@ -299,6 +299,7 @@ information about the governance of the io.js project, see
 * **Petka Antonov** ([@petkaantonov](https://github.com/petkaantonov)) <petka_antonov@hotmail.com>
 * **Yosuke Furukawa** ([@yosuke-furukawa](https://github.com/yosuke-furukawa)) <yosuke.furukawa@gmail.com>
 * **Alex Kocharin** ([@rlidwka](https://github.com/rlidwka)) <alex@kocharin.ru>
+* **Christopher Monsanto** ([@monsanto](https://github.com/monsanto)) <chris@monsan.to>
 
 Collaborators follow the [COLLABORATOR_GUIDE.md](./COLLABORATOR_GUIDE.md) in
 maintaining the io.js project.