Update repository links for consistency in `CONTRIBUTING.md`
Update repository links for consistency in `CONTRIBUTING.md`

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