add user guide link checker

.github/workflows/gh-pages-test-links.yml

@@ -0,0 +1,28 @@
+---
+  name: check user guide links
+
+  on:
+    pull_request: 
+      paths:
+        - "source/**"
+
+  permissions: {}
+  jobs:
+    check-links:
+      name: Test
+      runs-on: ubuntu-latest
+      permissions:
+        contents: read
+      steps:
+        - name: Checkout
+          id: checkout
+          uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4.1.6
+
+        - name: Lychee
+          id: lychee
+          uses: lycheeverse/lychee-action@2b973e86fc7b1f6b36a93795fe2c9c6ae1118621 # v1.10.0
+          env:
+            GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          with:
+            args: --verbose --no-progress './**/*.md' './**/*.html' './**/*.erb' --exclude-loopback --accept 403,200,429
+            fail: true