Dochubb is a client-side JavaScript documentation browser that pulls all of its documentation from markdown files in a Github repo.

ASP.NET server side code is used for the OAuth authentication with Github but you can easily replace it with simple authentication or convert it to some other server side language.

A working demo is available at http://dochubb.azurewebsites.net. GitHub will ask you to authorize the app so that it can use the GitHub API to read from the test repository.