Add docker images, push to temp registry and update docs

[jaseemabid]

The images are built with multi platform support like this:

$ docker buildx create --name mybuilder --use
$ docker buildx  build --push --platform linux/arm64,linux/amd64  -t olifant/simple-dash:latest .

The images require the user to mount a config file just as usual.

[jaseemabid]

PS: The images are pushed to my docker hub account here as an example, can rename that to something else if needed.