Update comments to reflect that this is a default referral test.

tests/data/slapd-ref-slave.conf

 #
-# referral slave slapd config -- for referral testing
+# slave slapd config -- for default referral testing
 #
 include		./data/slapd.at.conf
 include		./data/slapd.oc.conf

tests/scripts/test009-referral

 #! /bin/sh
 
 #
-# Test simple slave->master referral
+# Test default referral
 #
 
 if test $# -eq 0 ; then