Update makefs(8) man page to reflect the selection of default sector and disc

sizes based on the disc type.

usr.sbin/makefs/makefs.8

@@ -1,4 +1,4 @@
-.\"	$NetBSD: makefs.8,v 1.48 2013/08/05 18:49:58 reinoud Exp $
+.\"	$NetBSD: makefs.8,v 1.49 2013/08/06 09:43:41 reinoud Exp $
 .\"
 .\" Copyright (c) 2001-2003 Wasabi Systems, Inc.
 .\" All rights reserved.
@@ -33,7 +33,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd August 5, 2013
+.Dd August 6, 2013
 .Dt MAKEFS 8
 .Os
 .Sh NAME
@@ -401,15 +401,18 @@ The following keywords are supported:
 .It Sy disctype
 This can have the following values:
 .Bl -tag -width dvdramXbdreXdiskXXX -compact
-.It Sy cdrom , Sy dvdrom
+.It Sy cdrom , Sy dvdrom , Sy bdrom
 create a read-only fs
 .It Sy dvdram , Sy bdre , Sy disk
 create a rewritable fs without sparing for defective sectors
-.It Sy cdr , Sy dvdr
+.It Sy cdr , Sy dvdr , Sy bdr
 create a rewritable fs on once recordable media using a VAT
 .It Sy cdrw , Sy dvdrw
 create a rewritable fs with sparing for defective sectors
 .El
+When an optical media is selected here, the sectorsize and the default disc
+size is assumed unless given explicitly. For rom images the disc size is the
+minimum needed.
 .El
 .Sh SEE ALSO
 .Xr strsuftoll 3 ,