To make the use of your API as easy as possible for the end customer, you have a free hand in documenting.
Admin Portal
You can work freely with Markdown or rich text and create a folder structure according to your wishes. You can even create a folder, link it to git and get your documentation from there.
With the type rich text you get a graphical editor with which you can easily and conveniently create documentation. You can also use this type to create your documentation in html.
A summary of all HTML templates can be found here: CMS Template Library