Add missing reference to setsockopt(2) to "SEE ALSO" section.

lib/libc/sys/socket.2

@@ -1,4 +1,4 @@
-.\"	$NetBSD: socket.2,v 1.13 1999/03/22 19:45:10 garbled Exp $
+.\"	$NetBSD: socket.2,v 1.14 1999/06/24 20:16:31 tron Exp $
 .\"
 .\" Copyright (c) 1983, 1991, 1993
 .\"	The Regents of the University of California.  All rights reserved.
@@ -244,6 +244,7 @@ The socket cannot be created until sufficient resources are freed.
 .Xr poll 2 ,
 .Xr select 2 ,
 .Xr send 2 ,
+.Xr setsockopt 2 ,
 .Xr shutdown 2 ,
 .Xr socketpair 2 ,
 .Xr write 2