A key element of your prototype is its documentation: what is it? What can it do and how? The documentation will get people to understand your design, contribute to your code and help you make your prototype useful.
Here are a few starting points:
README.md: an important file at the root of your project where you describe what this is all about, how to use your project, what test you have done, who contributed, etc. A list of examples and articles here.
Change Log is a another useful file to communicate about the major changes and milestones your project. Some guidances about Change logs here.
Nice looking website out of your markdown with GitHub Pages. For example, this website has been automatically generated from the wheelchair-design-platform repository.