message: Update generate --site error message
diff: @@ -390,12 +390,12 @@ fn run() -> Result<(), failure::Error> {
  } else if let Some(matches) = matches.subcommand_matches("generate") {
  let name = matches.value_of("name").unwrap_or("worker");
  let site = matches.is_present("site");
  - let template_value = matches.value_of("template");
  + let template = matches.value_of("template");
  let mut target_type = None;
  let template = if site {
  - if template_value.is_some() {
  - failure::bail!("You cannot specify a template when generating a Workers Site. If you want to generate site boilerplate, run wrangler generate --site")
  + if template.is_some() {
  + failure::bail!("You cannot specify a template when generating a Workers Site. If you'd like to use the default site boilerplate, run wrangler generate --site. If you'd like to use another site boilerplate, omit the --site when running wrangler generate.")
  }
  "https://github.com/cloudflare/worker-sites-template"
  } else {
  @@ -404,7 +404,7 @@ fn run() -> Result<(), failure::Error> {
  }
  let default_template = "https://github.com/cloudflare/worker-template";
  - let template = template_value.unwrap_or(match target_type {
  + let template = template.unwrap_or(match target_type {
  Some(ref pt) => match pt {
  TargetType::Rust => "https://github.com/cloudflare/rustwasm-worker-template",
  _ => default_template,
  