Ask HN: Continues documentation for Github?

I'm an open-source developers on Github. I have many small and big repositories from one to one-hundred contributors in each project.

My main problem is with contributors and the projects is that when a new contributor come and ask me about the project, I have to describe whole project, methods, functions and... to him/her. That just waste my time.

I need a system that read my code from repository and build my code documentation (using document generating tools, Doxygen etc.) after each commit, so I have my updated document always and I can refer all new contributors to this document...

Does anyone know a system/solution like that?