Fix security issue: Add explicit permissions to GitHub Actions workflow

Co-authored-by: dev-testing-code <77578623+dev-testing-code@users.noreply.github.com>

Author: Copilot

.github/workflows/validate.yml

@@ -11,6 +11,8 @@ jobs:
   validate:
     name: Validate README and Links
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
 
     steps:
       - name: Checkout repository