ci: add markdown linting

Signed-off-by: Naseem <[email protected]>

.github/workflows/lint.yml

@@ -35,3 +35,24 @@ jobs:
 
     - name: Test Docs
       run: npm run docs-test
+
+  lint-markdown:
+    name: Lint changelog file
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Lint changelog file
+        uses: avto-dev/markdown-lint@v1
+        with:
+          # Commenting due to
+          # https://github.com/avto-dev/markdown-lint/blob/aab9be9823fcd706f6da3e6ad6c64874c23fbd4c/lint/rules/changelog.js#L51-L71
+          # TODO: adhere to, or overwrite above rule and uncomment rules
+          # rules: "/lint/rules/changelog.js"
+          config: "/lint/config/changelog.yml"
+          args: "./CHANGELOG.md"
+
+      - name: Lint markdown files
+        uses: avto-dev/markdown-lint@v1
+        with:
+          args: "./**/*.md -i ./CHANGELOG.md"