A few hints that sets may come in .tar.xz format (instead of .tgz)

usr.sbin/etcupdate/etcupdate.8

@@ -1,4 +1,4 @@
-.\"	$NetBSD: etcupdate.8,v 1.22 2014/06/12 14:07:13 apb Exp $
+.\"	$NetBSD: etcupdate.8,v 1.23 2018/11/21 20:18:11 martin Exp $
 .\"
 .\" Copyright (c) 2001-2008 The NetBSD Foundation, Inc.
 .\" All rights reserved.
@@ -27,7 +27,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd June 12, 2014
+.Dd November 20, 2018
 .Dt ETCUPDATE 8
 .Os
 .Sh NAME
@@ -204,9 +204,13 @@ extracted from a binary distribution of
 .Nx .
 The files that are distributed in the
 .Dq Pa etc.tgz
+or
+.Dq Pa etc.tar.xz
 set file must be present.
 The files that are distributed in the
 .Dq Pa xetc.tgz
+or
+.Dq Pa xetc.tar.xz
 set file are optional.
 The reference files from the specified directory will be copied to the
 .Pa temproot
@@ -216,7 +220,8 @@ The location of a set file
 (or
 .Dq "tgz file" )
 such as
-.Dq Pa etc.tgz
+.Dq Pa etc.tgz ,
+.Dq Pa etc.tar.xz
 or
 .Dq Pa xetc.tgz
 from a binary distribution of
@@ -230,9 +235,13 @@ Multiple
 options may be used to specify multiple set files.
 The
 .Dq Pa etc.tgz
+or
+.Dq Pa etc.tar.xz
 set file must be specified.
 The
 .Dq Pa xetc.tgz
+or
+.Dq Pa xetc.tar.xz
 set file is optional.
 .El
 .It Fl t Ar temproot