fix link

Author: vangj

jupyter/diabetes.html

@@ -41,7 +41,7 @@
     <svg id="bbn">
     </svg>
 
-    <script src="//cdnjs.cloudflare.com/ajax/libs/d3/3.5.3/d3.js"></script>
+    <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.3/d3.js"></script>
     <script src="https://cdn.jsdelivr.net/lodash/4.11.1/lodash.js"></script>
     <script src="https://rawgithub.com/cpettitt/graphlib/master/dist/graphlib.core.js"></script>
     <script src="https://rawgithub.com/cpettitt/dagre/master/dist/dagre.js"></script>