The non-reference docs have been moved!
The non-reference documentation for Docker Machine has been merged into the general documentation repo.
The conceptual and guide docs for Docker Machine are now here: https://github.com/docker/docker.github.io/tree/master/machine
The reference docs remain in this repo, at: https://github.com/docker/machine/tree/master/docs/reference
As always, the docs in the general repo remain open-source and we appreciate your feedback and pull requests!