uptime(1): Add EXAMPLES section

Add a simple example

Approved by:	manpages (bcr@)
Differential Revision:	https://reviews.freebsd.org/D26063

usr.bin/w/uptime.1

@@ -28,7 +28,7 @@
 .\"     @(#)uptime.1	8.2 (Berkeley) 4/18/94
 .\" $FreeBSD$
 .\"
-.Dd April 18, 1994
+.Dd August 18, 2020
 .Dt UPTIME 1
 .Os
 .Sh NAME
@@ -48,6 +48,11 @@ the number of users, and the load average of the system over the last
 .It Pa /boot/kernel/kernel
 system name list
 .El
+.Sh EXAMPLES
+.Bd -literal -offset indent
+$ uptime
+11:23AM  up  3:01, 8 users, load averages: 21.09, 15.43, 12.79
+.Ed
 .Sh SEE ALSO
 .Xr w 1
 .Sh HISTORY