fix(CONTRIBUTING): update label format for good first issues (#2056)

Author: jgarciao

CONTRIBUTING.md

@@ -32,7 +32,7 @@ We use a vouch system. This exists because AI makes it trivial to generate plaus
 
 ### Finding Work
 
-Issues labeled [`good-first-issue`](https://github.com/NVIDIA/OpenShell/issues?q=is%3Aissue+is%3Aopen+label%3Agood-first-issue) are scoped, well-documented, and friendly to new contributors. Start there. If you need guidance, comment on the issue.
+Issues labeled [`good first issue`](https://github.com/NVIDIA/OpenShell/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22) are scoped, well-documented, and friendly to new contributors. Start there. If you need guidance, comment on the issue.
 
 All open issues are actionable — if it's in the issue tracker, it's ready to be worked on.