...and you can add generation-time markdown while they are created, so e.g. you can have graphs generated and inserted in the documentation (see https://hexdocs.pm/stoker/Stoker.html to have and idea of how useful that can be - that's created with https://github.com/l3nz/say_cheez_ex).

Or you can have a library that creates SVG that embeds the SVG it creates and its source code, like https://hexdocs.pm/contex/Contex.Gallery.BarCharts.html