ci: scope down permissions for check-docs.yml

Author: AdnaneKhan

.github/workflows/check-docs.yml

@@ -21,6 +21,9 @@ on:
       - 'lambda-extension/**'
       - 'Cargo.toml'
 
+permissions:
+  contents: read
+
 jobs:
   build-runtime:
     runs-on: ubuntu-latest