message: Typo fix in arp_packet example.
diff: @@ -76,7 +76,7 @@ fn main() {
  None => {
  writeln!(
  io::stderr(),
  - "USAGE: packetdump <NETWORK INTERFACE> <TARGET IP>"
  + "USAGE: arp_packet <NETWORK INTERFACE> <TARGET IP>"
  )
  .unwrap();
  process::exit(1);
  @@ -88,7 +88,7 @@ fn main() {
  None => {
  writeln!(
  io::stderr(),
  - "USAGE: packetdump <NETWORK INTERFACE> <TARGET IP>"
  + "USAGE: arp_packet <NETWORK INTERFACE> <TARGET IP>"
  )
  .unwrap();
  process::exit(1);
  