Harden markdownlint. (#2412)

.github/workflows/markdownlint.yml

@@ -26,13 +26,14 @@ jobs:
       statuses: write
 
     steps:
-      - uses: actions/checkout@8f4b7f84864484a7bf31766abe9204da3cbe65b3
-      - name: Use Node.js
-        uses: actions/setup-node@64ed1c7eab4cce3362f8c340dee64e5eaeef8f7c
+      - name: Harden Runner
+        uses: step-security/harden-runner@0d381219ddf674d61a7572ddd19d7941e271515c # v2.9.0
         with:
-          node-version: 16.x
-      - name: Run Markdownlint
-        run: |
-          echo "::add-matcher::.github/workflows/markdownlint-problem-matcher.json"
-          npm i -g markdownlint-cli2
-          markdownlint-cli2 "**/*.md"
+          egress-policy: audit
+
+      - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
+      - uses: DavidAnson/markdownlint-cli2-action@b4c9feab76d8025d1e83c653fa3990936df0e6c8 # v16.0.0
+        with:
+          config: ".markdownlint-cli2.jsonc"
+          globs: "**/*.md"
+      

.markdownlint-cli2.jsonc

@@ -62,6 +62,13 @@
         "MD051": false
     },
     "ignores": [
-        ".github/"
+        ".github/",
+        "README.md",
+        "CONTRIBUTING.md",
+        "SUPPORT.md",
+        "ThirdPartyNotices.md",
+        "SECURITY.md",
+        "CODE_OF_CONDUCT.md",
+        "issues-policy.md"
     ]
 }