lorder: add deprecation notice

lorder has not been used by the base system since 0e1e341b48 and
hasn't really been necessary for a very long time.

PR:		259254 [exp-run]
Reviewed by:	arichardson (earlier)
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D30080

usr.bin/lorder/lorder.1

@@ -28,12 +28,17 @@
 .\"     @(#)lorder.1	8.2 (Berkeley) 4/28/95
 .\" $FreeBSD$
 .\"
-.Dd December 20, 2021
+.Dd March 21, 2023
 .Dt LORDER 1
 .Os
 .Sh NAME
 .Nm lorder
 .Nd list dependencies for object files
+.Sh DEPRECATION NOTICE
+.Nm
+is obsolete and may not be present in
+.Fx 14
+and later.
 .Sh SYNOPSIS
 .Nm
 .Ar