add document, fix tooltip position issue

lib/ui/tooltip.html

@@ -0,0 +1,44 @@
+<div>
+    <h1>tooltip</h1>
+    <hr />
+    <p>
+        给某个元素或者页面上含有 title 属性的元素设置一个统一样式的 tooltip。
+    </p>
+    <h2>setTooltip</h2>
+    <code>function setTooltip(container: HTMLElement, content: string | HTMLElement): void</code>
+    <h3>container: HTMLElement</h3>
+    <p>
+        要设置 tooltip 的元素
+    </p>
+    <h3>content: string | HTMLElement</h3>
+    <p>
+        要设置的 tooltip 内容，允许为字符串或者 HTML 元素
+    </p>
+    <h2>resolveTooltip</h2>
+    <code>function resolveTooltip(container: HTMLElement): HTMLElement</code>
+    <h3>container: HTMLElement</h3>
+    <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>
+    <h2>示例</h2>
+    <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;
+  &lt;button title="Test to send request through XMLHttpRequest."&gt;Test&lt;/button&gt;
+&lt;/div&gt;
+
+&lt;script type="text/javascript"&gt;
+  window["lib-ui"].resolveCheckbox(document.querySelector("#checkbox-sample"));
+&lt;/script&gt;</pre>
+    <div id="tooltip-sample">
+        <blockquote title="From MDN Website">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.</blockquote>
+        <button title="Test to send request through XMLHttpRequest.">Test</button>
+    </div>
+    <script type="text/javascript">
+        window["lib-ui"].resolveTooltip(document.querySelector("#tooltip-sample"));
+    </script>
+</div>