added link to enghub

Author: eloymg

semgrep/custom-rules.yaml

@@ -8,6 +8,6 @@ rules:
         - "*.yml"
     message: >
       Do not use actions/create-github-app-token. Use the organization's
-      approved alternative for generating GitHub App tokens.
+      approved [alternative for generating GitHub App tokens](https://enghub.grafana-ops.net/docs/default/component/deployment-tools/platform/vault/github-app-token-broker-migration-guide/).
     languages: [generic]
     severity: WARNING