I need to maintain the docker-compose environment as I should update the
hosting environment and we wanna deploy the docker image.
The ecosystem is using docker, I use podman.
I therefore need to configure docker hub as look up registry for podman
for unqualified images.
There doesn't seem to be a `toTOML` nixpkgs method. That's why I write
the contents of the file myself.
I now already have nix shells as well as compose.yaml files for
projects. Those were split and are now migrated into a common folder.
That should keep main directory clean and self document that those files
relate to projects, not home manager or systems.