docs(contributing): fix the dead labels.yml link on main (#804)

main links to z-shell/.github/.github/lib/labels.yml, which became a 404
when that duplicate was removed in z-shell/.github#471. The corrected
link already exists on next via #802, but main requires branches to be
up to date and its required Trunk Check fails on this 404, so the
promotion that would carry the fix is blocked by the fix's absence.

Applies the same one-line correction directly to main to break that
deadlock. Identical to the change already on next, so the branches
converge cleanly.

Co-authored-by: Sall <ss-o@users.noreply.github.com>

Author: ss-o

community/00_contributing/05_project_management.mdx

@@ -106,7 +106,7 @@ Labels are applied manually during triage or by approved organization
 automation.
 
 The source of truth lives in
-[`z-shell/.github/.github/lib/labels.yml`](https://github.com/z-shell/.github/blob/main/.github/lib/labels.yml).
+[`z-shell/.github/lib/labels.yml`](https://github.com/z-shell/.github/blob/main/lib/labels.yml).
 Rollout across repositories is handled through organization maintenance automation.
 
 ### Work Type Labels