iproute2: Fill in the ip-netns.8 manpage

Document ip netns monitor.

Add a few senteces describing each command.  The manpage was looking
very scrawny.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/man/man8/ip-netns.8 b/man/man8/ip-netns.8
index 349ee7e..ff08232 100644
--- a/man/man8/ip-netns.8
+++ b/man/man8/ip-netns.8
@@ -1,4 +1,4 @@
-.TH IP\-NETNS 8 "20 Dec 2011" "iproute2" "Linux"
+.TH IP\-NETNS 8 "16 Jan 2013" "iproute2" "Linux"
 .SH NAME
 ip-netns \- process network namespace management
 .SH SYNOPSIS
@@ -23,6 +23,9 @@
 .BR "ip netns exec "
 .I NETNSNAME command ...
 
+.ti -8
+.BR "ip netns monitor"
+
 .SH DESCRIPTION
 A network namespace is logically another copy of the network stack,
 with its own routes, firewall rules, and network devices.
@@ -54,11 +57,52 @@
 their traditional location in /etc.
 
 .SS ip netns list - show all of the named network namespaces
+
+This command displays all of the network namespaces in /var/run/netns
+
 .SS ip netns add NAME - create a new named network namespace
+
+If NAME is available in /var/run/netns/ this command creates a new
+network namespace and assigns NAME.
+
 .SS ip netns delete NAME - delete the name of a network namespace
+
+If NAME is present in /var/run/netns it is umounted and the mount
+point is removed.  If this is the last user of the network namespace the
+network namespace will be freed, otherwise the network namespace
+persists until it has no more users.  ip netns delete may fail if
+the mount point is in use in another mount namespace.
+
 .SS ip netns exec NAME cmd ... - Run cmd in the named network namespace
 
+This command allows applications that are network namespace unaware
+to be run in something other than the default network namespace with
+all of the configuration for the specified network namespace appearing
+in the customary global locations.  A network namespace and bind mounts
+are used to move files from their network namespace specific location
+to their default locations without affecting other processes.
+
+.SS ip netns monitor - Report as network namespace names are added and deleted
+
+This command watches network namespace name addition and deletion events
+and prints a line for each event it sees.
+
 .SH EXAMPLES
+.PP
+ip netns list
+.RS
+Shows the list of current named network namespaces
+.RE
+.PP
+ip netns add vpn
+.RS
+Creates a network namespace and names it vpn
+.RE
+.PP
+ip netns exec vpn ip link set lo up
+.RS
+Bring up the loopback interface in the vpn network namespace.
+.RE
 
 .SH SEE ALSO
 .br