Update README to include information from official image docs

[ninjarobot]

The official image docs contain all the details about the image. It would be best to include that information here as well.

[jrvosse]

Dave, I assume you have edit rights on https://hub.docker.com/_/swipl/ right?
If you the "Full Description" you should have access to the markdown.
Can't you just copy/paste this into the markdown README.md here?
Thanks,
Jacco (I do not know how to get the markdown used on Docker for projects I do not have edit rights)

[ninjarobot]

@jrvosse the page there is generated from a few markdown files. I can pull them together, just need to take the time to do it.