Create PullRequestValidator action

.github/workflows/PullRequestValidator

@@ -0,0 +1,18 @@
+name: Pull Request Validator
+on:
+  pull_request:
+    branches: [ "master" ]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+      - name: Install Node.js
+        uses: actions/setup-node@v2
+        with:
+          node-version: '19'
+      - name: Install Antora and Lunr
+        run: npm i antora @antora/lunr-extension
+      - name: Run Antora
+        run: npx antora antora-playbook.yml