message: fix route clap description
diff: @@ -248,7 +248,7 @@ fn run() -> Result<(), failure::Error> {
  .subcommand(
  SubCommand::with_name("delete")
  .arg(environment_arg.clone())
  - .about("Delete multiple keys and their values from a namespace")
  + .about("Delete a route by id")
  .arg(
  Arg::with_name("route_id")
  .help("the id associated with the route you want to delete (find using `wrangler route list`)")
  