link logo image to revealjs.com

README.md

@@ -1,5 +1,7 @@
 <p align="center">
+  <a href="https://revealjs.com">
   <img src="https://hakim-static.s3.amazonaws.com/reveal-js/logo/v1/reveal-black-text.svg" alt="reveal.js" width="450">
+  </a>
   <br><br>
   <a href="https://github.com/hakimel/reveal.js/actions"><img src="https://github.com/hakimel/reveal.js/workflows/tests/badge.svg"></a>
   <a href="https://slides.com/"><img src="https://s3.amazonaws.com/static.slid.es/images/slides-github-banner-320x40.png?1" alt="Slides" width="160" height="20"></a>