Add lychee link checker (#80)

* Add lychee link checker

* Add exclusion for local links and email (test data)

* Exclude localhost

* Exclude loopback

* Add localhost regex :/

* Fix regex :'(

* Fix argument formatting :'(

* Fix formatting :'''(

* Exclude lesson specific urls

* Update job name to clarify purpose

* Remove link local exclusion

Author: marcduiker

.github/workflows/code-tour-and-links-watcher.yml

@@ -0,0 +1,34 @@
+name: CodeTour and Links Watcher
+
+on:
+    pull_request:
+        types: [opened, edited, synchronize, reopened]
+    workflow_dispatch:
+
+permissions:
+    contents: read
+    pull-requests: write
+
+jobs:
+    codetour-links-watcher:
+        runs-on: ubuntu-latest
+        steps:
+            - name: 'Checkout source code'
+              uses: actions/checkout@v2
+        
+            - name: 'Watch CodeTour changes'
+              uses: pozil/[email protected]
+              with:
+                  repo-token: ${{ secrets.GITHUB_TOKEN }}
+                  tour-path: '.tours/'
+            
+            - name: Link Checker
+              id: lychee
+              uses: lycheeverse/[email protected]
+              with:
+                args:  --verbose --no-progress --exclude-mail --exclude-loopback --exclude "https?://localhost.*" "https://sandbox.api.sap.com.*" "https://azure-university-app-config.*" "https://192.168.7.108.*" -- "**/*.md"
+              env:
+                GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}
+            
+            - name: Fail if there were link errors
+              run: exit ${{ steps.lychee.outputs.exit_code }}