Don't put a shell prompt in the example since none of the other man

pages do it.  Also, don't use brackets to indicate optional options in
the example; instead, add a paragraph below the example explaining it.

bin/ls/ls.1

@@ -363,9 +363,15 @@ The following is how to do an
 .Nm
 listing sorted by size (and shows why
 .Nm
-does not need this functionality).
+does not need a separate option for this):
 .Pp
-.Dl "% ls -l | sort [-r] -n +4"
+.Dl "ls -l | sort -n +4"
+.Pp
+Additionally, you may want to use the
+.Fl r
+flag to
+.Xr sort 1
+to get the results sorted from largest to smallest (a reverse sort).
 .Sh DIAGNOSTICS
 The
 .Nm