Update index.html

index.html

@@ -54,7 +54,7 @@
 
 <div id = "container">
     <div id = "tree">
-        <script src="http://d3js.org/d3.v3.min.js"></script>
+        <script src="https://d3js.org/d3.v3.min.js"></script>
         <script>
 
             var treeData = [