Added graph example 25 to gallery

index.html

@@ -328,6 +328,12 @@ The source code of the examples can be found in the
       <div>hierarchical layout predefined</div>
     </a>
   </div>
+  <div class="thumb">
+    <a href="examples/graph/25_physics_configuration.html">
+      <img src="img/gallery/graph/25_physics_configuration.png">
+      <div>physics configuration</div>
+    </a>
+  </div>
   <div class="thumb">
     <a href="examples/graph/graphviz/graphviz_gallery.html">
       <img src="img/gallery/graph/graphviz_gallery.png">