Update docs

docs/index.html

@@ -101,8 +101,10 @@ $(document).ready(function(){initNavTree('index.html',''); initResizable(); });
   <div class="headertitle"><div class="title">Penning trap simulation </div></div>
 </div><!--header-->
 <div class="contents">
-<div class="textblock"><p><a class="anchor" id="md_README"></a> </p>
-<h1><a class="anchor" id="autotoc_md1"></a>
+<div class="textblock"><p><a class="anchor" id="md_README"></a> </p><div class="image">
+<img src="100_particles.gif" alt=""/>
+</div>
+    <h1><a class="anchor" id="autotoc_md1"></a>
 Credits</h1>
 <p>The Doxygen theme used here is <a href="https://github.com/jothepro/doxygen-awesome-css">doxygen-awesome-css</a>. </p>
 </div></div><!-- PageDoc -->