Only check links in Markdown files, if Markdown files changed (#1866)

* Only check links in Markdown files, if Markdown files changed

Signed-off-by: Shmuel Kallner <kallner@il.ibm.com>

* Applied review suggestions

Signed-off-by: Shmuel Kallner <kallner@il.ibm.com>

---------

Signed-off-by: Shmuel Kallner <kallner@il.ibm.com>

Author: shmuelk

.github/workflows/md-link-check.yml

@@ -18,14 +18,30 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
+  
+  check-for-markdown-files:
+    runs-on: ubuntu-latest
+    outputs:
+      src: ${{ steps.filter.outputs.src }}
+    steps:
+      - name: Checkout source
+        uses: actions/checkout@v7
+      - uses: dorny/paths-filter@v4
+        id: filter
+        with:
+          filters: |
+            src:
+              - '**/*.md'
+
   lychee:
     name: Check Markdown Links
+    needs: check-for-markdown-files
     # pull_request_target fires even when GITHUB_TOKEN creates the PR (e.g. the
     # release-notes bot). pull_request does not. We register pull_request_target
     # so bot-created PRs get a "skipped" conclusion that satisfies branch
     # protection, but we skip all real work: pull_request already covers human
     # PRs, and running twice would cause the concurrency group to cancel one run.
-    if: github.event_name != 'pull_request_target'
+    if: github.event_name != 'pull_request_target' && ${{ needs.check-changes.outputs.src == 'true' }}
     runs-on: ubuntu-latest
 
     steps: