Updating it as a part of the release process, so it should be updated in coordination with downloads being posted to the website.
For the suggestions, you are welcome to open issues for the docker improvements that you’d like to see. 
This is well known. The struggle is that having a well-designed docker image that is useful to a large number of use-cases requires a person doing the work that knows how to design a docker image well that will satisfy a large number of use-cases. This is something that, I believe, the current set of companies sponsoring FDB work lack.
I’ve been hopeful that this is an area where the community would help define or create the appropriate solution. If anyone would like to post a design doc for what a well-designed docker image would look like, it’s overly welcome. Early in FDB’s OSS history, there was an initial community PR that tried to do this, and the work stalled out for a variety of reasons. I think it highlights why we likely haven’t seen continued progress, unfortunately. The current docker image was meant as the smallest step forward that still yielded a meaningful improvement.
My current hope has been that from the upcoming FDB summit, some folk will give talks and release what they’ve done for Kubernetes/docker, and that will help to push the area along.