Add a list of device types for use with "rndctl -t ${typename}".

sbin/rndctl/rndctl.8

@@ -1,4 +1,4 @@
-.\"	$NetBSD: rndctl.8,v 1.16 2008/11/06 15:58:16 apb Exp $
+.\"	$NetBSD: rndctl.8,v 1.17 2009/01/04 12:01:43 apb Exp $
 .\"
 .\" Copyright (c) 1997 Michael Graff
 .\" All rights reserved.
@@ -26,7 +26,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd November 6, 2008
+.Dd January 4, 2009
 .Dt RNDCTL 8
 .Os
 .Sh NAME
@@ -90,6 +90,20 @@ All devices of type
 are altered or displayed.
 This is mutually exclusive with
 .Fl d .
+.Pp
+The available types are:
+.Bl -tag -width "diskx"
+.It Ic disk
+Physical hard drives.
+.It Ic net
+Network interfaces.
+.It Ic tape
+Tape devices.
+.It Ic tty
+Terminal, mouse, or other user input devices.
+.It Ic rng
+Random number generators.
+.El
 .El
 .Sh FILES
 .Bl -tag -width /dev/urandomx -compact