message: Added warning for site in unauthenticated preview
diff: @@ -180,7 +180,7 @@ fn unauthenticated_upload(target: &Target) -> Result<Preview, failure::Error> {
  log::info!("address: {}", create_address);
  let mut target = target.clone();
  - // KV namespaces are not supported by the preview service unless you authenticate
  + // KV namespaces and sites are not supported by the preview service unless you authenticate
  // so we omit them and provide the user with a little guidance. We don't error out, though,
  // because there are valid workarounds for this for testing purposes.
  if !target.kv_namespaces.is_empty() {
  @@ -189,6 +189,13 @@ fn unauthenticated_upload(target: &Target) -> Result<Preview, failure::Error> {
  );
  target.kv_namespaces = Vec::new();
  }
  + if target.site.is_some() {
  + message::warn(
  + "Sites are not supported in preview without setting API credentials and account_id",
  + );
  + target.site = None;
  + }
  +
  let script_upload_form = upload::form::build(&target, None)?;
  let client = http::client();
  let res = client
  