Add README to RPZ tests

bin/tests/system/rpz/README

@@ -0,0 +1,30 @@
+Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+
+See COPYRIGHT in the source root or http://isc.org/copyright.html for terms.
+
+The test setup for the RPZ tests prepares a query perf tool and sets up
+policy zones.
+
+
+Name servers
+------------
+
+ns1 is the root server.
+
+ns2 and ns4 are authoritative servers for the various test domains.
+
+ns3 is the main rewriting resolver.
+
+ns5 and ns7 are additional rewriting resolvers.
+
+ns6 is a forwarding server.
+
+
+Updating the response policy zones
+----------------------------------
+
+test1, test2, test3, test4, test5, and test6 are dynamic update files.  These
+updates are made against ns3.  The script function "start_group" is called to
+start an new batch of tests that may depend on certain server updates.  The
+function takes an optional file name and if provided the server updates are
+performed before executing the test batch.