chore: ignore 429 (too busy) responses from github w/ markdown link checker (#1553)

Author: kevmoo

.github/markdown-link-check-config.json

@@ -0,0 +1,5 @@
+{
+  "retryOn429": true,
+  "retryCount": 5,
+  "fallbackRetryDelay": "30s"
+}

.github/workflows/markdown_linter.yml

@@ -12,7 +12,13 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd
-      - uses: gaurav-nelson/github-action-markdown-link-check@5c5dfc0ac2e225883c0e5f03a85311ec2830d368
+        with:
+          fetch-depth: 0
+      # sadly, markdown-link-check has a bug where it doesn't handle config files
+      # so we pin to a version that doesn't have that bug
+      - run: |
+          npm install -g markdown-link-check@3.14.2
+          find . -name "*.md" -not -path './.git/*' -not -path './node_modules/*' -print0 | xargs -0 -n1 markdown-link-check -c .github/markdown-link-check-config.json
   markdown_lint:
     runs-on: ubuntu-latest
     steps: