Update Starter template to use the Markdown component (#270)

Uses the Markdown component in the Tour component.

packages/create-astro/src/templates/starter/astro.config.mjs

@@ -7,7 +7,7 @@ export default {
     // '.jsx': 'react',    // Set this to "preact" or "react" to determine what *.jsx files should load
   },
   buildOptions: {
-    // site: '',           // Your public domain, e.g.: https://my-site.dev/. Used to generate sitemaps and canonical URLs.
+    // site: 'http://example.com',           // Your public domain, e.g.: https://my-site.dev/. Used to generate sitemaps and canonical URLs.
     // sitemap: true,      // Generate sitemap (set to "false" to disable)
   },
   devOptions: {

packages/create-astro/src/templates/starter/src/components/Tour.astro

@@ -4,31 +4,31 @@
     </div>
 
     <section>
-        <h2>🚀 Project Structure</h2>
-        <p>Inside of your Astro project, you'll see the following folders and files:</p>
+        <Markdown>
+            ## 🚀 Project Structure
 
-        <pre><code class="tree">/
-├── public/
-│   ├── robots.txt
-│   └── favicon.ico
-├── src/
-│   ├── components/
-│   │   └── Tour.astro
-│   └── pages/
-│       └── index.astro
-└── package.json</code>
-        </pre>
+            Inside of your Astro project, you'll see the following folders and files:
 
-            <p>
-                Astro looks for <code>.astro</code> or <code>.md</code> files in the <code>src/pages/</code> directory.
-                Each page is exposed as a route based on its file name.
-            </p>
+            ```
+            /
+            ├── public/
+            │   ├── robots.txt
+            │   └── favicon.ico
+            ├── src/
+            │   ├── components/
+            │   │   └── Tour.astro
+            │   └── pages/
+            │       └── index.astro
+            └── package.json
+            ````
 
-            <p>
-                There's nothing special about <code>src/components/</code>, but that's where we like to put any Astro/React/Vue/Svelte/Preact components.
-            </p>
+            Astro looks for `.astro` or `.md` files in the `src/pages/` directory.
+            Each page is exposed as a route based on its file name.
 
-            <p>Any static assets, like images, can be placed in the <code>public/</code> directory.</p>
+            There's nothing special about `src/components/`, but that's where we like to put any Astro/React/Vue/Svelte/Preact components.
+
+            Any static assets, like images, can be placed in the `public/` directory.
+        </Markdown>
     </section>
 
      <section>