fix(onboarding): add line break

lib/workers/repository/onboarding/pr/index.js

@@ -28,6 +28,8 @@ async function ensureOnboardingPr(config, packageFiles, branches) {
 {{BASEBRANCH}}
 {{PRLIST}}
 
+---
+
 :question: If you have any questions, try reading the [Docs](https://renovatebot.com/docs), particularly the Getting Started section.
 Also, you can post questions about your config in [Renovate's Config Help repository](https://github.com/renovatebot/config-help/issues).
 `;