Is there something wrong with how GitHub renders the Markdown you generate? The two examples given in the repo are not exactly human-readable and apart from bullet points I didn't notice any styling.
Yes, you're right. Looks like Github Doesn't render the Markdown I'm generating properly. You can use http://dillinger.io/ (online markdown visualizer) to visualize markdown properly.
Also, Feel free to contribute! Next step would be adding some extended styling with CSS rules (although that's not entirely portable) or read links in JSON and convert them to (name)[url] Markdown format.