From the submission history, it appears that the OP is a fan of docker, so it's likely the site was shared with that in mind, rather than him/her being the author of the linked content.
It is on github, and pull requests are welcome. It is currently written for Docker 0.5. I will keep it up to date, and when we hit 1.0 I'll look at getting some hard copies made, if there is a demand.
I still need to pick a license, not sure what is best for a book, open to suggestions.