Update self-hosting example to use HTML5 element

app/views/asciicasts/_download.html.erb

@@ -40,13 +40,11 @@
         <pre><code>&lt;html>
 &lt;head>
   &lt;link rel="stylesheet" type="text/css" href="/asciinema-player.css" />
-  &lt;script src="/asciinema-player.js">&lt;/script>
 &lt;/head>
 &lt;body>
-  &lt;div id="player-container">&lt;/div>
-  &lt;script>
-    asciinema.player.js.CreatePlayer('player-container', '/<%= page.asciicast_download_filename %>', { width: <%= page.asciicast_width %>, height: <%= page.asciicast_height %> });
-  &lt;/script>
+  &lt;asciinema-player src="/<%= page.asciicast_download_filename %>" cols="<%= page.asciicast_width %>" rows="<%= page.asciicast_height %>">&lt;/asciinema-player>
+  ...
+  &lt;script src="/asciinema-player.js">&lt;/script>
 &lt;/body>
 &lt;/html></code></pre>