Improve Initial CO Creation

When Registry is set up, creating the first CO (other than the COmanage CO) is a little clunky. No enrollment flows can be defined, because a CMP admin can't currently execute an enrollment flow if the admin isn't also in that CO. So the first CO admin has to be invited (ie: via email).

At a minimum, add some documentation ("Setting Up Your First CO"). Better would be to simplify the creation of the first CO and CO admin.