add link to the github repo on the front page

templates/index.html

@@ -5,6 +5,7 @@
     <p>Hello, stranger! </p>
     <p>Forget is a service that automatically deletes your old posts once everyone has forgotten about them. After all, why shouldn't computers forget too?</p>
 </section>
+
 <section>
 <h2>Features</h2>
 <ul>
@@ -13,8 +14,10 @@
     <li>Pick between deleting posts older than a date, posts past a post count, or both</li>
     <li>Optionally mark posts that you want to preserve forever, by giving them a like</li>
     <li>Upload a tweet archive if your twitter account has more tweets than the twitter api will return</li>
+    <li><a href="https://github.com/codl/forget">Free and Open Source software</a></li>
 </ul>
 </section>
+
 <section>
 <h2>Sign in</h2>
 <p>Sound good to you? <a href="/login/twitter">Log in with Twitter</a></p>