Put back in wormsim.org link

Author: pgleeson

index.html

@@ -132,6 +132,7 @@ <h1>Enter the worm!</h1>
 					Thanks to our Kickstarter backers we developed WormSim, 
 					an interactive way to play with the worm in your browser!
 				</p>
+				<a class="btn btn-large btn-primary" href="http://wormsim.org" target="_blank">Learn more</a>
 				<a class="btn btn-large btn-primary" href="https://www.youtube.com/watch?v=QaCRNX0hdwU"
 				   target="_blank">Watch a video</a>
 			    </div>