@goldyfruit was principally responsible for that image, so is best equipped to describe it, though I should note that both it and the original Mycroft-core are abandonware. The state of affairs:
As to the nature of the thing itself, I should also clarify that there are two elements. The Assistant, either Mycroft-core or a derivative, is software. That docker image, and the various Mycroft-based smart speaker images, are each separate, more or less opinionated implementations of the Assistant. Put differently, you aren’t running a docker version of the Mark II, you’re running a dockerized version of the Assistant.
Goldyfruit is now maintaining OVOS’ docker image (see FAQ) which we regard as much more “official” than MycroftAI did theirs. Our image kinda resembles what we put on a Mark II, when you run our smart speaker distro, but we’d sooner put most retail customers on NeonOS (see FAQ) which runs a heavily configured OVOS stack on a heavily opinionated system, with a whole bunch of their own utilities atop. Largely what we were hoping for in the first place, you might say, but not dockerized, afaik.