ip6addrctl.8: Reference RFC 6724 as well

Commit e695500 updated the policy table
to match RFC 6724, which obsoletes RFC 3484.

Add a reference to RFC 6724 as well.

usr.sbin/ip6addrctl/ip6addrctl.8

@@ -27,7 +27,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd September 25, 2001
+.Dd August 10, 2024
 .Dt IP6ADDRCTL 8
 .Os
 .\"
@@ -111,6 +111,14 @@ comments and are ignored.
 .%T "Default Address Selection for IPv6"
 .%N RFC 3484
 .Re
+.Rs
+.%A "Dave Thaler"
+.%A "Richard Draves"
+.%A "Arifumi Matsumoto"
+.%A "Tim Chown"
+.%T "Default Address Selection for Internet Protocol Version 6 (IPv6)"
+.%N RFC 6724
+.Re
 .\"
 .Sh HISTORY
 The