Add a Dockerfile for following the commands

[rustymagnet3000]

Love the book @lizrice.

Any chance you can add a Dockerfile to this repo so people can better follow along with the early chapters ( capabilities and cgroups ). In the "Examples" section of the book I can see you are using a Virtual Machine with Vagrant. I wanted to avoid running a full VM. If this is not possible [ due to immutability of containers, or some other interesting reason? ] it would be awesome to call it out.

I setup two Docker Containers with Alpine and Ubuntu as the base image, when following along with the book. I would constantly hit config issues that slowed my reading down.