Add MD linting

.github/workflows/jekyll.yml

@@ -26,9 +26,18 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
+  # Lint Markdown file job
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: DavidAnson/markdownlint-cli2-action@v15
+      with:
+        globs: '**/*.md'
   # Build job
   build:
     runs-on: ubuntu-latest
+    needs: lint
     steps:
       - name: Checkout
         uses: actions/checkout@v3