The important piece of information here is to make forks of both repos,
batphone and serval-dna, before cloning them, so that the "git submodule
update" command (which now uses a relative URL) will succeed.
So that git will fetch submodules using the same transport (https:,
git:, ssh:) as they used to clone Batphone.
Now, people who fork batphone must also fork serval-dna at the same
server location, otherwise "git submodule init" will fail.
in INSTALL.md consistent. Note: if the .git/config file of the
project was consistent with this documentation, the project would
be buildable behind http/https-only firewalls that are typical
in the corporate world.