Add action description

Author: Jelle-S

.github/workflows/drupal-update.yml

@@ -163,7 +163,8 @@ jobs:
             automated pr
           draft: true
 
-      - uses: marocchino/sticky-pull-request-comment@v2
+      - name: Add composer.lock diff as PR comment
+        uses: marocchino/sticky-pull-request-comment@v2
         if: ${{ steps.cpr.outputs.pull-request-number }}
         with:
           header: composer-diff