Move privileges section in database admin docs

Move privileges section in database admin docs

The "Privileges" section in the RST database administration
documentation was tucked away in the middle of a section on principal
operations.  Move it out and put it between policy operations and
kdb5_util operations, without changing its content.

(We may want to replace this whole section with a reference to the
appropriate part of the kadmind man page, but that requires a bit of
reconciliation since the kadmind man page doesn't document
restrictions yet.)

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@25775 dc483132-0cff-0310-8789-dd5450dbe970