Add the content sidebar of a singe markdown file to the website

Now the IoTDB [website](https://iotdb.apache.org/UserGuide/Master/QuickStart/QuickStart.html) has the left sidebar to guide through different markdown files,
but lacks the right sidebar to guide through the different sections in a single markdown file.
It's easy to get lost when reading a long markdown without a content sidebar.

未指定源文件、测试或入口点。首先检查链接的 IoTDB 网站，查找其 Markdown 页面是如何生成的；确认章节标题是如何表示的。完成标准是：较长的单页 Markdown 文档会显示右侧的内容侧边栏，其中链接到文档的各个章节。

由索引模型根据 Issue 内容生成。