genetics: Add a "Credits" section

This page has been receiving a lot of attention after being posted to
Reddit and Hacker News. As some people have pointed out, the idea of
using genetic algorithms to approximate fine art has been done by many
people. I am not trying to pass this idea off as my own, so I think it
is necessary to clearly attribute my sources.

s/genetics/index.html

@@ -175,6 +175,16 @@ <h1 class="headline-title">
         involved in the process, feel free to fork the
         <a href="https://github.com/ChrisCummins/chriscummins.github.io" target="_blank">source code repository</a>
         and submit a pull request.
+
+        <center><h5>Credits</h5></center>
+
+        The code is my own, the idea is not. Full credit goes to
+        <a href="http://rogeralsing.com/2008/12/07/genetic-programming-evolution-of-mona-lisa/" target="_blank">Roger Alsing</a>
+        for the idea of using genetic algorithms to approximate fine
+        art. Further thanks to
+        <a href="https://twitter.com/jseidelin" target="_blank">Jacob Seidelin</a>
+        for writing a JavaScript implementation that inspired me to
+        create this.
       </div> <!-- /.span6 -->
 
       <div class="span6">