Missing MAINTAINERS file

[thaJeztah]

I'm working on preparing the open source repositories for the new centralized maintainers file, but noticed this repository does not yet have a MAINTAINERS file.

I can create a PR to fix this, but I'm not sure who should be included as maintainer(s).

@abronan are you the only maintainer, or should I add other people here?

for reference, see docker/opensource#35 and moby/moby#18321