New lint CI. Fix some issues.

.github/workflows/ci.yml

@@ -8,6 +8,10 @@ jobs:
   markdown-lint:
     runs-on: ubuntu-latest
     steps:
+      - uses: actions/setup-node@v2
+        with:
+          node-version: '16'
+          cache: 'npm'
       - uses: actions/checkout@v2
       - name: Install packages
         run: sudo gem install mdl
@@ -15,5 +19,7 @@ jobs:
         run: mdl . -r ~MD036,~MD024,~MD004,~MD029
       - run: pip install -r requirements.txt
       - run: mkdocs build --strict
+      - run: npm install
+      - run: node .github/manual_lint.js
         # Suppress 036 Emphasis used instead of a header
         # Suppress 024 Multiple headers with the same content