Make repository links consistent in `CONTRIBUTING.md`
Make repository links consistent in `CONTRIBUTING.md`

RaptorRCX/exercism.io,RaptorRCX/exercism.io,RaptorRCX/exercism.io,treiff/exercism.io,tejasbubane/exercism.io,tejasbubane/exercism.io,RaptorRCX/exercism.io,treiff/exercism.io,treiff/exercism.io,tejasbubane/exercism.io,treiff/exercism.io,tejasbubane/exercism.io