added legend phylo tree

conekt/templates/tree.html

@@ -58,6 +58,7 @@
             <div id="phyd3" style="height:600px">
                 <div id="chart-loader" style="widht:800px;height:600px"></div>
             </div>
+	    <p>(The heatmaps are normalized by row. <strong style="color:#fff08e">Light yellow</strong> cells indicate no/low expression, <strong style="color:#000682">dark blue</strong> cells show the maximum expression. <strong>White</strong> cells lacking a border are missing values.)</p>	
             <hr />
         </div>
 
@@ -170,4 +171,4 @@
             });
         </script>
     {% endif %}
-{% endblock %}
+{% endblock %}