message: Add demo frontmatter
diff: const fetch = require("node-fetch");
  +const fs = require("fs");
  +const path = require("path");
  +
  +const DEMOS_PATH = path.resolve("static/demos");
  (async function() {
  const response = await fetch("https://unpkg.com/@ionic/docs/core.json");
  @@ -25,8 +29,20 @@ function writePage(page) {
  }
  function renderFrontmatter({ tag }) {
  + const frontmatter = {
  + title: tag
  + };
  +
  + const demoPath = `api/${tag.slice(4)}/index.html`;
  + if (fs.existsSync(path.join(DEMOS_PATH, demoPath))) {
  + frontmatter.demoUrl = `/docs/demos/${demoPath}`;
  + frontmatter.demoSourceUrl = `https://github.com/ionic-team/ionic-docs/tree/main/static/demos/${demoPath}`;
  + }
  +
  return `---
  -title: ${tag}
  +${Object.entries(frontmatter)
  + .map(([key, value]) => `${key}: ${value}`)
  + .join("\n")}
  ---
  import Tabs from '@theme/Tabs';
  import TabItem from '@theme/TabItem';
  