I think it is enabled "per integrated" but when I went through https://github.com/apps/dependabot-preview/installations/697211 (which I tried earlier via Marketplace, but I couldn't see JenkinsCI org, only your link worked), it updated "permissions" and my suspicions were correct, now I can see it in the Settings > integrations. So I'm guessing it's adding some hooks or sth.
If you enable it on all repos via github you need to add a config file for it to be picked up
seems to work fine
Yup, if there's any blogpost to be updated via a PR, let me know, I'll be happy to do this, otherwise thanks for quick reaction, it works now and created PRs already :clap: