* Use /usr/pkg/bin/bash path to bash
* Setup cloud-init, since the image expects it
* Explicitly use the "default" network, to avoid libvirt using its
  default heuristics which is affected by existing network bridges
  on the host machine.

Also added an explicit MIT license for this. The upstream license is
available here; while also hinting to Creative Commons: CC BY-SA 4.0, it
states that "[a]ll contributions to this project are licensed under the
following license", and then quotes the MIT license.

* https://gitlab.com/gitlab-org/gitlab-docs/-/blob/main/LICENSE
* https://gitlab.com/gitlab-org/dco/blob/master/README.md

I asked a question in
https://gitlab.com/gitlab-org/dco/-/merge_requests/6#note_2216867608 to
try and clarify this explicitly.