.github: Add markdown linter

Signed-off-by: Joe Stringer <[email protected]>

Author: joestringer

.github/workflows/lint.yaml

@@ -0,0 +1,11 @@
+on: [push, pull_request]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: DavidAnson/markdownlint-cli2-action@v17
+      with:
+        globs: |
+          **/*.md