Update README and make it more explicit
Update README and make it more explicit

This patch updates the README file and makes it explicit that the config
file should be copied into ~/.marconi (which is suppose to be a
directory).

Change-Id: I08a0ad74cca7068197d3cef35000b07c75076012

openstack/zaqar,rackerlabs/marconi,openstack/zaqar,openstack/zaqar,openstack/zaqar