Documenting Playbooks

All,
we are in the process of switching from another product to ansible at work. So we are working on our “how we want to operate” type stuff, to fill in gaps we currently have. So, we are documenting roles in a README with each role, which makes sense, so that you have all the options, etc right here. So my question, is do any of you document your playbooks? If so how are you organizing that inside a project structure.

–John