Community maintained Docker config for the knot server

Add Spindle container image build #47

Open psychedeli.ca
targeting main from psychedeli.ca/knot-docker:spindle
Open opened by and assigned to psychedeli.ca
targeting main from psychedeli.ca/knot-docker:spindle
Commits 8

add docs around variables
rename releases to all
add legacy releases task and info on how to build past releases
fix adduser/group commands in spindle stage
update readme to reference the spindle and document how to build images using docker bake
add docker bake config for building edge releases
add spindle to docker-compose and configure builds for each image
add build stage for the spindle server