* Mention Docker SDK for Python instead of docker-py / docker.
* Docs fixes.
* Add myself as docker_container author.
* Use array syntax for running command.
* Break long lines.
* Avoid failure when docker_version is None.
* Improve docker-py vs. docker note in requirements.
* Canonicalize Docker SDK for Python upgrade instructions.
* Split long line.
* Make it clearer which hostnames are meant.