[Docs/Workbench] Document how to clone repositories over HTTPS
You have to:
- Have ARVADOS_API_TOKEN in your environment
- Set up the helper in your user configuration: do the
git config --systemsteps on the shell install guide, but say
git config --userinstead.
This is a little bit of a hassle, but still probably easier than cloning over SSH for people who don't use it regularly. Document it in the User Guide and in Workbench, the same places we talk about cloning over SSH.