gh action check for broken links

.github/workflows/link_check.yml

@@ -0,0 +1,15 @@
+name: Check Markdown links
+
+on: 
+  push:
+    branches:
+    - master
+  schedule:
+  - cron: "0 0 * * 1"
+
+jobs:
+  markdown-link-check:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@master
+    - uses: gaurav-nelson/github-action-markdown-link-check@v1