docs(demo): add open graph and twitter card meta tags for link previews

Author: alvin000009238

demo/index.html

@@ -9,6 +9,12 @@
   <meta property="og:title" content="壢中成績 - Android App">
   <meta property="og:description" content="一鍵掌握班排與科目表現，為壢中學生量身設計的成績查詢 App。">
   <meta property="og:type" content="website">
+  <meta property="og:url" content="https://score.clhs.dev/">
+  <meta property="og:image" content="https://score.clhs.dev/assets/icon.png">
+  <meta name="twitter:card" content="summary">
+  <meta name="twitter:title" content="壢中成績 - Android App">
+  <meta name="twitter:description" content="一鍵掌握班排與科目表現，為壢中學生量身設計的成績查詢 App。">
+  <meta name="twitter:image" content="https://score.clhs.dev/assets/icon.png">
   <link rel="icon" type="image/png" href="./assets/icon.png">
   <link rel="preconnect" href="https://fonts.googleapis.com">
   <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>