to the comments in named.conf to describe to the user how to create it.
(named.conf does not use /etc/namedb/s by default anyway so us not
pre-created it in the mtree does not hurt us terribly).
Adjust rc.conf to run named in sandbox, adjust mtree to add /etc/namedb/s
subdirectory (user bind, group bind) to hold secondaries, adjust
comments in named.conf to reflect new secondary scheme. (Note that
core read-only zone files are left owned by root, increasing security even
more).
