How does render markdown to HTML-documentation?

Hi everybody,

as I would like to have a similar documentation for my own project I’d like to know how GitLab technically renders its documentation – residing in an git-project itself – to

From what I’ve read so far the documentation team currently uses redcarpet but wants to move to kramdown

What I would like to know is how the menues (top/right) and the search (top) is included for the documenation on Is that done via the renderers aswell and if not how do you accomplish this? Is there any documentation on how the documentation is built? Or can you point me to some configuration files which are responsible for rendering the documentation?

Thanks in advance,