Update .github/workflows/documentation-links.yml

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Author: henryiii

.github/workflows/documentation-links.yml

@@ -16,7 +16,7 @@ concurrency:
 jobs:
   documentation-links:
     runs-on: ubuntu-latest
-    if: github.event.pull_request.head.repo.full_name == 'python/peps'
+    if: github.event.repository.fork == false
     steps:
       - uses: readthedocs/actions/preview@v1
         with: