Add a brief description.

git-svn-id: svn://bind10.isc.org/svn/bind10/branches/parkinglot@498 e5f2f494-b856-4b98-b285-d166d9295462

README

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+This is the source for the BIND 10 testing branch known as
+the parkinglot. This is a simple authoritative server used
+to provide identical records for many zones, such as in
+a DNS parking service.
 
 BUILDING