Remove dead 2004 link to list of blacklists, from Sevan Janiyan.

Point at wikipedia's list of blacklists instead, some are DNS-only but there
are a few rsyncable ones in there (including a good commercial one and some
free ones).

src/etc/mail/spamd.conf

@@ -1,4 +1,4 @@
-# $OpenBSD: spamd.conf,v 1.7 2016/05/11 06:33:48 jsg Exp $
+# $OpenBSD: spamd.conf,v 1.8 2016/06/01 21:55:47 sthen Exp $
 #
 # spamd(8) configuration file, read by spamd-setup(8).
 # See also spamd.conf(5).
@@ -13,8 +13,10 @@
 # Lists specified with the :white: capability apply to the previous
 # list with a :black: capability.
 #
-# As of November 2004, a place to search for blacklists is
-#     http://spamlinks.net/filter-bl.htm
+# As of June 2016, a place to search for blacklists is
+#     http://en.wikipedia.org/wiki/Comparison_of_DNS_blacklists
+# - most of these are DNS-based only and cannot be used with spamd(8),
+# but some of the lists also provide access to text files via rsync.
 
 all:\
 	:nixspam: