better document about default rrtype

[reedjc]

-b in manpage says "If bailiwick is
specified, but rrtype is not specified, then a default rrtype of ANY
will be used."

But that default rrtype is same regardless if -b is set or not.
It does set it in the REST URI simply because the DNSDB API requires it when bailiwick is set.
Document about default rrtype elsewhere in this manual.