setkey appeared in FreeBSD 4.0

PR:		212551
Approved by:	bcr (mentor)
MFC after:	4 days
Differential Revision:	https://reviews.freebsd.org/D8105

sbin/setkey/setkey.8

@@ -29,7 +29,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd July 3, 2015
+.Dd October 3, 2016
 .Dt SETKEY 8
 .Os
 .\"
@@ -713,6 +713,8 @@ The
 .Nm
 utility first appeared in WIDE Hydrangea IPv6 protocol stack kit.
 The utility was completely re-designed in June 1998.
+It first appeared in
+.Fx 4.0 .
 .\"
 .Sh BUGS
 The