Update the readme to include working examples.
Update the readme to include working examples.

With the 0.10.0 plugin changes you will need to preserve state
between runs (to keep the .terraform directory with plugins)

So include the mounted volume in the examples (so we maintain
copy and pasteable instructions that just work)

Also update the working directory because there isn't clear instructions
on which directory the files should get added to which results in confusion

hashicorp/docker-hub-images