In general, it does not make sense to do it because you will lose the update when you restart the container. Even though it is possible to create an image based on a running container is not really the paradigm behind containers.

What you should do is download an updated image, stop the one you are ...

sure

https://github.com/danielhoperez/domoticz-docker

it is still very precarious, and not yet connected with docker hub

I am just playing around with it but I have built a couple of images.

https://hub.docker.com/r/danielhoperez/domoticz-builder
I use this image to build domoticz (to avoid bloating the actual domoticz image)

and just 10 minutes ago I've created
https://hub.docker.com/r/danielhoperez/domoticz ...