Add a stolperstein image to the header

_includes/header.html

@@ -1,6 +1,6 @@
 <nav class="navbar no-print">
   <div class="container navbar-title" role="banner">
-    <a href="{{ site.url }}{{ site.baseurl }}/">{{ site.title }}</a>
+    <img src="{{ site.baseurl }}/images/icon.png" alt="" height="15"> <a href="{{ site.url }}{{ site.baseurl }}/">{{ site.title }}</a>
   </div>
   <div class="container" role="navigation">
     <ul class="navbar-list">