add legacy support of checkbox, add documents for cookie/lgres/request

lib/ui/tooltip.html

@@ -20,9 +20,9 @@
     <p>
         给此元素下的所有含有 title 属性的子元素设置成统一样式的 tooltip
     </p>
+    <hr />
     <h2>示例</h2>
-    <pre>
-&lt;div id="tooltip-sample"&gt;
+    <pre>&lt;div id="tooltip-sample"&gt;
   &lt;blockquote title="From MDN Website"&gt;To send an HTTP request, create an XMLHttpRequest object, open a URL, and
     send the request. After the transaction completes, the object will contain useful information such as the
     response body and the HTTP status of the result.&lt;/blockquote&gt;