bug 957802: Update contribute.json
bug 957802: Update contribute.json

* Move "home" from old Platform dev page to MDN Durable Team homepage
* Update IRC handle list
* Fix mentored bug link
* Drop "goodfirstbug" link, not used in current process
* Swap keyword "vagrant" for "docker"

safwanrahman/kuma,jwhitlock/kuma,SphinxKnight/kuma,Elchi3/kuma,a2sheppy/kuma,SphinxKnight/kuma,a2sheppy/kuma,a2sheppy/kuma,a2sheppy/kuma,a2sheppy/kuma,escattone/kuma,Elchi3/kuma,Elchi3/kuma,safwanrahman/kuma,jwhitlock/kuma,safwanrahman/kuma,escattone/kuma,safwanrahman/kuma,jwhitlock/kuma,mozilla/kuma,SphinxKnight/kuma,mozilla/kuma,Elchi3/kuma,SphinxKnight/kuma,mozilla/kuma,SphinxKnight/kuma,safwanrahman/kuma,SphinxKnight/kuma,Elchi3/kuma,safwanrahman/kuma,escattone/kuma,mozilla/kuma,jwhitlock/kuma,jwhitlock/kuma,mozilla/kuma