Fix link to I-nominated in CONTRIBUTING.md

[dwijnand]

No description provided.

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @alexcrichton (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

[matklad]

@bors r+

Thanks!

[bors]

📌 Commit 463f207 has been approved by matklad

[bors]

⌛ Testing commit 463f207 with merge d8b2031...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: matklad
Pushing d8b2031 to master...

[dwijnand]

btw I noticed highfive linked me to the rust CONTRIBUTING.md rather than cargo's, so I proposed to change that over at rust-lang/highfive#132.