Add link checking to template (#15)

Useful for links in README etc.

.github/workflows/links.yaml

@@ -0,0 +1,19 @@
+---
+name: links
+
+on:
+  push:
+    branches:
+      - main
+      - renovate/**
+  pull_request:
+
+jobs:
+  links:
+    runs-on: ubuntu-latest
+    timeout-minutes: 2
+    steps:
+      - name: Check links
+        uses: UCL-MIRSG/.github/actions/links@f1eea08573626b08d2c0419d6cd365ea07d7dadd # v0
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}