Update docker tutorial to use standard install procedure

 * Use the standard installation instruction instead of the master
   version: 0.7 has been out for some time now.
 * As a result, switch to `sudo docker` instead of `sudo ./docker`.
 * Correct minor typos
Make the docker tutorial work with newer Docker, and add a warning about not using it for deployment.
upcase "Buildbot".
Small adjustments to docker tutorial.

Add a note about issues with Docker itself, and rephrase the
don't-deploy-this-way warning slightly.

Fixes #2989.
Merge pull request #1368 from sa2ajj/eight-update-docker-docs

Backport Docker documentation updates to eight