Re-enable markdown link checker. (#8212)

The upstream fix for link syntax has landed.

- Uncomment the workflow and bump the version.
- Add a config file to encourage retries.

.github/workflows/markdown-links.yml

@@ -1,19 +1,18 @@
-# TODO: Re-enable when https://github.com/gaurav-nelson/github-action-markdown-link-check/pull/126 lands.
+name: Check Markdown links
 
-#name: Check Markdown links
-#
-#on:
-#  push:
-#    branches:
-#      - master
-#  pull_request:
-#    branches: [master]
-#
-#jobs:
-#  markdown-link-check:
-#    runs-on: ubuntu-latest
-#    steps:
-#      - uses: actions/checkout@v3
-#      - uses: gaurav-nelson/github-action-markdown-link-check@v1.0.13
-#        with:
-#          check-modified-files-only: 'yes'
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches: [master]
+
+jobs:
+  markdown-link-check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: gaurav-nelson/github-action-markdown-link-check@1.0.14
+        with:
+          check-modified-files-only: 'yes'
+          config-file: '.md-link-check.json'

.md-link-check.json

@@ -0,0 +1,6 @@
+{
+    "retryOn429": true,
+    "retryCount": 5,
+    "fallbackRetryDelay": "30s",
+    "aliveStatusCodes": [200, 206, 503]
+}