Merge branch 'master' of github.com:ahpaleus/building-secure-contracts into ahpaleus_master

Author: montyly

.github/workflows/check_links.yml

@@ -0,0 +1,20 @@
+name: Check Markdown links
+
+on:
+  push:
+    branches:
+      - master
+      - dev
+  pull_request:
+  schedule:
+    # run CI at 09:00, on day 1 of the month even if no PRs/merges occur
+    - cron:  '0 9 1 * *'
+
+jobs:
+  markdown-link-check:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@master
+    - uses: gaurav-nelson/github-action-markdown-link-check@v1
+      with:
+        use-quiet-mode: 'yes'