add link to github repo

Author: papjuli

topics/Intro.html

@@ -10,6 +10,8 @@ <h2>Introduction</h2>
     <span class="tooltip" data-tooltip-id="tooltip-Tutte">
   W.T.Tutte</span>. The page assumes basic knowledge of graph theory.</p>
 
+  <p>If you would like to fork or contribute to the project, please visit the <a href="https://github.com/papjuli/rubber-band-method" target="_blank">GitHub repository</a>.</p>
+
   <hr></hr>
 
   <p>This web page illustrates how one simple mathematical idea: replacing the edges of a graph by rubber bands, can be used to design a variety of graph algorithms:</p>