Update code comment link to contributor's guide

Editor assessment

This is a well-behaved commit mechanically: valid type, imperative subject, no trailing period, PR reference included, and a length well within limits. The debatable point is typing — updating a code comment's link is content documentation, so `docs` would arguably describe it better than `chore`; many tooling setups surface docs changes separately in changelogs, and this would currently be invisible there. As a maintainer chore it is still defensible since no shipped behavior changes either way. No scope and no body, but neither is needed for a one-line edit. It correctly signals no version bump, which matches the actual impact. In short: structurally clean, with the type choice being the only real point of discussion.