message: wrangler secret should show usage
diff: @@ -272,6 +272,7 @@ fn run() -> Result<(), failure::Error> {
  "{} Generate a secret that can be referenced in the worker script",
  emoji::SECRET
  ))
  + .setting(AppSettings::SubcommandRequiredElseHelp)
  .subcommand(
  SubCommand::with_name("put")
  .about("Create or update a secret variable for a script")
  