message: Update metas.ts
  use page title for metas if metas.title not exists
diff: @@ -67,6 +67,10 @@ export default function (userOptions?: Partial<Options>) {
  return;
  }
  + if (page.title && !metas.title) {
  + metas.title = page.title;
  + }
  +
  const { document } = page;
  const url = site.url(page.data.url as string, true);
  const icon = metas.icon
  