【fix】修改主题存储方式为cookie review by luoxiao

Author: chenxianhuii

build/jsdocs/template/tmpl/layout.tmpl

@@ -4,6 +4,7 @@
     <meta charset="utf-8">
     <script src="scripts/prettify/prettify.js"></script>
     <script src="scripts/prettify/lang-css.js"></script>
+    <script src="../../examples/js/utils.js"></script>
     <script src="../../examples/js/theme/themeConfig.js"></script>
     <script src="../../examples/js/theme/theme.js"></script>
 <script type="text/javascript">

examples/js/theme/theme.js

@@ -52,7 +52,7 @@ document.addEventListener("DOMContentLoaded", function() {
 });
 
 function initSkin() {
-  var skin = window.sessionStorage.getItem('theme') || 'light';
+  var skin = utils.getCookie('theme') || 'light';
   var bodyElem = document.querySelector('body');
   bodyElem.classList.remove("light", "dark");
   bodyElem.classList.add(skin);