We're working on docs, see
https://docs.blue-nebula.org. Writing docs takes a lot of time, many iterations, and only few people are willing to invest the required time into this.
I'll try to find time to publish a small guide there, and update this post then. Docker images are available for 1.6 (maintained by me),
https://quay.io/repository/theassassin/redeclipse, they are compatible with our game (you just need to set the environment variable "SERVERMASTER=master.blue-nebula.org").
Never heard of linuxgsm. They're of course free to use our software and integrate it into theirs.