Currently, all roles (inside roles/) are Git submodules, and work on the roles themselves should take place in the upstream Role repository.
Adding a role (submodule)
cd roles
git submodule add https://github.com/dev/repo
Updating all roles (submodules)
git submodule update --recursive --remote
After updating roles, commit and push all changes, and make sure the collection works as expected. Then tag the new version of the collection and push the tag.