Indentation is not correct for yaml file https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/13/html/advanced_overcloud_customization/ansible-based-registration#annotations:17651fcb-25b6-4ac3-91e8-db5d14e1a115
Have pushed a fix. Should be correct now: https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/13/html-single/advanced_overcloud_customization/#ansible-based-registration