link logo in demo deck to revealjs.com

demo.html

@@ -29,7 +29,9 @@
 			<!-- Any section element inside of this container is displayed as a slide -->
 			<div class="slides">
 				<section>
-					<img src="https://static.slid.es/reveal/logo-v1/reveal-white-text.svg" alt="reveal.js logo" style="height: 180px; margin: 0 auto 4rem auto; background: transparent;" class="demo-logo">
+					<a href="https://revealjs.com">
+						<img src="https://static.slid.es/reveal/logo-v1/reveal-white-text.svg" alt="reveal.js logo" style="height: 180px; margin: 0 auto 4rem auto; background: transparent;" class="demo-logo">
+					</a>
 					<h3>The HTML Presentation Framework</h3>
 					<p>
 						<small>Created by <a href="http://hakim.se">Hakim El Hattab</a> and <a href="https://github.com/hakimel/reveal.js/graphs/contributors">contributors</a></small>