To download for local edits:
git clone https://github.com/SpinWearables/SpinWearables.github.io.git
Then download the submodules (one for the main page with the book, and one for the literary code documentation).
make register_submodule_updates
You can edit websitesource and firmwaresource as if they were standalone git repositories. Consult their own README files. When you are done (and have commited and pushed all the changes for these two repositories), you can run
make publish
in order to update the live page. This would perform a git push on the entire repo, carrying over any changes of the subrepos.