Added GitHub action to check links

Author: joachimmetz

.github/workflows/check_links.yml

@@ -0,0 +1,24 @@
+name: check_links
+on:
+  pull_request:
+    branches:
+    - main
+  push:
+    branches:
+    - main
+  # TODO: make this a cron action
+  # runs every monday at 9 am
+  # schedule:
+  #   - cron: "0 9 * * 1"
+permissions: read-all
+jobs:
+  check-links:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+      - uses: gaurav-nelson/github-action-markdown-link-check@v1
+        with:
+          use-quiet-mode: 'yes'
+          use-verbose-mode: 'yes'
+          config-file: '.github/workflows/markdown.links.config.json'
+          folder-path: 'docs/'

.github/workflows/markdown.links.config.json

@@ -0,0 +1,7 @@
+{
+  "ignorePatterns": [
+    {
+      "pattern": "^tags/#"
+    }
+  ]
+}