message: Add Twitter meta tags.
diff: <meta property="og:title" content={title} />
  <meta property="og:type" content={type} />
  <meta property="og:url" content={url} />
  +
  + <!-- https://developer.twitter.com/en/docs/twitter-for-websites/cards/overview/markup -->
  + <meta name="twitter:card" content="summary" />
  + <meta name="twitter:site" content="@gitpod" />
  + <meta name="twitter:creator" content="@gitpod" />
  </svelte:head>
  