Refresh the First-run instructions.

- Move to pip
- Don't activate the virtualenv (IMO not necessary)
- Put less emphasis on docker.
- Remove the use of tail
- Refresh the logs (2011 and 2009 !)
- Explain a bit more what the commands are for.
Don't remove the `.. code-block:: bash` lines, either -- those are important, as otherwise the code is treated as Python.