feat: Add new workflow to block direct module reference changes

Author: lamATnginx

.github/workflows/block-changes.yml

@@ -0,0 +1,18 @@
+name: Block specific changes
+
+on:
+  pull_request:
+
+jobs:
+  block-direct-markdown-module-changes:
+    name: Block modifying Markdown Module Reference files directly
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@4
+      - name: Check if changes came from nginx.org action
+        id: check_pr_source
+        run: |
+          PR_SRC=$(jq -r ".pull_request.user.login" < "$GITHUB_EVENT_PATH")
+          echo $PR_SRC
+