Falsy statement in installation guide.

It says:
"Almost done! For next steps on configuration:
  https://github.com/progrium/dokku#configuring"
after bootstrapping..
Merge pull request #290 from Jeewes/patch-1

Deprecated statement in installation guide.
Added domains plugin which implements `dokku domains` commands for
working with VHOST files.
Replaced /home/git with $DOKKU_ROOT.