Document the -network=netname/prefixlength syntax. Requested in

PR 26891 by Arto Selonen.

Also some mdoc improvements.

usr.sbin/mountd/exports.5

@@ -1,4 +1,4 @@
-.\"	$NetBSD: exports.5,v 1.28 2006/09/18 16:03:36 wiz Exp $
+.\"	$NetBSD: exports.5,v 1.29 2006/10/08 16:35:19 apb Exp $
 .\"
 .\" Copyright (c) 1989, 1991, 1993
 .\"	The Regents of the University of California.  All rights reserved.
@@ -29,7 +29,7 @@
 .\"
 .\"     @(#)exports.5	8.3 (Berkeley) 3/29/95
 .\"
-.Dd September 18, 2006
+.Dd October 8, 2006
 .Dt EXPORTS 5
 .Os
 .Sh NAME
@@ -108,7 +108,7 @@ user credentials on the server.
 Export options are specified as follows:
 .Pp
 .Sm off
-.Fl maproot No = Sy user
+.Fl maproot No = Ar user
 .Sm on
 The credential of the specified user is used for remote access by root.
 The credential includes all the groups to which the user is a member
@@ -117,7 +117,7 @@ on the local machine (see
 The user may be specified by name or number.
 .Pp
 .Sm off
-.Fl maproot No = Sy user:group1:group2:...
+.Fl maproot No = Ar user : group1 : group2 : ...
 .Sm on
 The colon separated list is used to specify the precise credential
 to be used for remote access by root.
@@ -126,11 +126,11 @@ Note that user: should be used to distinguish a credential containing
 no groups from a complete credential for that user.
 .Pp
 .Sm off
-.Fl mapall No = Sy user
+.Fl mapall No = Ar user
 .Sm on
 or
 .Sm off
-.Fl mapall No = Sy user:group1:group2:...
+.Fl mapall No = Ar user : group1 : group2 : ...
 .Sm on
 specifies a mapping for all client uids (including root)
 using the same semantics as
@@ -202,14 +202,14 @@ use the
 flag, which implies
 .Fl public ,
 .Sm off
-.Fl mapall No = Sy nobody
+.Fl mapall No = Ar nobody
 .Sm on
 and
 .Fl ro .
 .Pp
 A
 .Sm off
-.Fl index No = Sy file
+.Fl index No = Ar file
 .Sm on
 option can be used to specify a file whose handle will be returned if
 a directory is looked up using the public filehandle (WebNFS).
@@ -264,12 +264,19 @@ Using the full domain specification for a hostname can normally
 circumvent the problem of a host that has the same name as a netgroup.
 The third case is specified by the flag
 .Sm off
-.Fl network No = Sy netname
+.Fl network No = Ar netname Op No / Ar prefixlength
 .Sm on
 and optionally
 .Sm off
-.Fl mask No = Sy netmask .
+.Fl mask No = Ar netmask .
 .Sm on
+The netmask mey be specified either by attaching a
+.Ar prefixlength
+to the
+.Fl network
+option, or by using a separate
+.Fl mask
+option.
 If the mask is not specified, it will default to the mask for that network
 class (A, B or C; see
 .Xr inet 4 ) .