robots.txt : added URL to sitemap with static copy (/s/) of the web

Add sitemap URL to robots.txt in GitHub Actions workflow

Author: VitSimon

.github/workflows/toPages.yml

@@ -116,6 +116,8 @@ jobs:
                  "$url" -o "$hlpdir/$name"
           done
 
+          echo "Sitemap: https://helpviewer.github.io/s/sitemap.xml" >> robots.txt
+
     - name: Commit and push changes
       run: |
         git config user.name "github-actions[bot]"