In upstream, foremanctl will be provided in parallel to the current installer. In the foreman-documentation repo, we need to create a structure to support that. This structure should enable writers to start preparing foremanctl-based documentation while also being able to keep publishing foremanctl-free docs.

Based on initial brainstorming, creating a new flavor named "foremanctl" seems like a good approach. This would utilize a conditional defined as ifdef::foremanctl + ifndef::foremanctl to include or exclude foremanctl content.

Possible alternatives are:

• Creating separate foremanctl guides (this is the approach currently being taken with the installation guide in https://github.com/theforeman/foreman-documentation/pull/4087 but would not work well for parallel foremanctl-based and foremanctl-free publishing)
• Using AsciiDoctor tabs (that worked for https://docs.theforeman.org/3.16/Quickstart/index-katello.html but would not support situations where whole sections would disappear with foremanctl).
• Creating a foremanctl branch to hold all the foremanctl documentation and then merging it to 'master' (because 'master' would keep getting regular updates not related to foremanctl, this would mean a lot of overhead maintenance with constant rebases and potential merge conflicts)