Edit the playbook.yml file by adding the new repository under
"sources", with the branch or branches that should be deployed, and the path
where the antora.yml file is found.
For the site to rebuild when there is an update, you need to add a webhook in the repo. In the Netlify panel, go to Site Settings > Build & deploy > Build hooks, and copy the hook URL. In the repo that is being added, go to Settings > Webhooks, and add a webhook using this URL and the default settings.