route(8): Add an example how to print the routing tables

The manual page currently doesn't show an example how to print
the routing table, so add one and .Xr netstat while here.

PR:		231579
Reported by:	Pekka Järvinen <pekka dot jarvinen at gmail dot com>
Reviewed by:	debdrup
MFC after:	5 days
Differential Revision:	https://reviews.freebsd.org/D29702

sbin/route/route.8

@@ -28,7 +28,7 @@
 .\"     @(#)route.8	8.3 (Berkeley) 3/19/94
 .\" $FreeBSD$
 .\"
-.Dd January 9, 2019
+.Dd April 11, 2021
 .Dt ROUTE 8
 .Os
 .Sh NAME
@@ -453,6 +453,10 @@ Delete a static route from the routing table:
 Remove all routes from the routing table:
 .Pp
 .Dl route flush
+.Pp
+List all routing tables:
+.Pp
+.Dl netstat -r
 .Sh DIAGNOSTICS
 .Bl -diag
 .It "add [host \&| network ] %s: gateway %s flags %x"
@@ -493,6 +497,7 @@ The next-hop gateway should be reachable through a different route.
 .El
 .Sh SEE ALSO
 .\".Xr esis 4 ,
+.Xr netstat 1 ,
 .Xr netintro 4 ,
 .Xr route 4 ,
 .Xr arp 8 ,