Docker external network `dbs` is not automatically created.

This is a companion issue to #9648. I know some projects like to have issues to go with the pull requests that address them-- apologies for the extra cruft if you don't think that's helpful.

The gist is that the docker-compose.yml file suggests that the docker external network `dbs` will be created by the makefile if it doesn't already exist. That used to happen, but when cookiecutter was implemented for h, that was not brought along.

The real fix, of course, would be to promote the creation of this network to within the cookiecutter, but I'm not sure where else in your tech stack that might be used and what other implications it might have.