Update ff tools README.md, use ff_netstat -rnW to display wider device name.

Author: jfb8856606

tools/README.md

@@ -102,7 +102,7 @@ Examples:
 
        ./sbin/route -p 0 flush
 
-    FreeBSD uses `netstat -rn ` to list the route table which we havn't ported,
+    FreeBSD uses `netstat -rnW ` to list the route table which we havn't ported,
     you can execute the following command instead, `-d` means debug mode, `-v`
     means verbose.
        ./sbin/route -p 0 -d -v flush