Add markdownlint workflow

.github/workflows/lint.yml

@@ -27,3 +27,14 @@ jobs:
 
       - name: Run eslint
         run: npm run lint
+
+  lint:
+    name: Lint Markdown
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out Git repository
+        uses: actions/checkout@2541b1294d2704b0964813337f33b291d3f8596b # tag=v3
+      - name: Set up problem matcher
+        uses: xt0rted/markdownlint-problem-matcher@b643b0751c371f357690337d4549221347c0e1bc # tag=v1.1.0
+      - name: Run markdownlint
+        run: npx --package markdownlint-cli markdownlint '**/*.md' --ignore node_modules

.markdownlint.yaml

@@ -0,0 +1,19 @@
+# MD013/line-length
+MD013: false
+
+# MD033/no-inline-html
+
+MD033: false
+
+# MD025/single-title
+MD025:
+  # Ignore front matter 'title' property, it is not used in generated markup
+  front_matter_title: ''
+
+# MD026/no-trailing-punctuation
+MD026:
+  # Allow headings to end with '?'
+  punctuation: '.,;:!'
+
+# MD028/no-blanks-blockquote
+MD028: false