Adding broken links check using github actions

Github action for checking broken links in the markdown files.
This check is triggered on PRs and push.

Signed-off-by: Vijayan Balasubramanian <[email protected]>

.github/workflows/links.yml

@@ -0,0 +1,25 @@
+name: Link Checker
+on:
+  push:
+    branches:
+      - "*"
+  pull_request:
+    branches:
+      - "*"
+
+jobs:
+  linkchecker:
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: lychee Link Checker
+        id: lychee
+        uses: lycheeverse/[email protected]
+        with:
+          args: --accept=200,403,429  "**/*.html" "**/*.md" "**/*.txt" "**/*.json" --exclude "https://github.com/\[your*" --exclude "https://localhost:9200" --exclude-mail
+        env:
+          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}
+      - name: Fail if there were link errors
+        run: exit ${{ steps.lychee.outputs.exit_code }}