Hi Daniel,
I'm not very familiar with Github Pages, but it seems that we could do
this by including the main repository as a submodule of the website
repository (maybe /src?) and then using the "include" Liquid to render
the Markdown file.
Otherwise, we'd have to implement some sort of push hook in the source
code repository, and that'd be quite a bit more complicated. I guess
we should try the submodule option first.
Antonio