Added check for dead links and fixed dead links

.github/workflows/gh-pages.yml

@@ -67,3 +67,12 @@ jobs:
       - name: Deploy to GitHub Pages
         id: deployment
         uses: actions/deploy-pages@v1
+
+  check:
+    runs-on: ubuntu-latest
+    needs: deploy
+    steps:
+      - name: Setup Node
+        uses: actions/setup-node@v3
+      - run: npm install linkinator
+      - run: npx linkinator https://flightcontrol-master.github.io/MOOSE/ --recurse