Documentation request for the feature defined in: https://bugzilla.redhat.com/show_bug.cgi?id=1476904 This will be Tech Preview for OSP-13. The documentation source can be started from the upstream docs: https://docs.openstack.org/tripleo-docs/latest/install/advanced_deployment/ansible_config_download.html
We also should document that Ceph (external and director deployed), Octavia, and Skydive won't work with config-download in OSP-13. There's also no UI support in 13. These are part of the reason why the feature is considered Tech Preview in 13 and won't be GA supported until 14.
This content has been reviewed by James Slagle and Omri Hochman. Should be ready for peer review: https://doc-stage.usersys.redhat.com/documentation/en-us/red_hat_openstack_platform/13/html/director_installation_and_usage/configuring-the-overcloud-with-ansible