feat(docs): add search functionality to docs site

### Feature Description

Hi Team,
Can we have filter/search functionality on left menu may be on top can have on input box and provide filter functionality

### Use Case

Let say I have been landed to the URL - https://material.angular.io/components/table/examples
And I wanted to see the spinner component and I don't have idea where is spinner component and where to scroll the page.
In this case if I could see the search functionality would be very useful for me to search "Spinner" and then I can get the spinner component options.

Hence this additional feature will provide good experience to users. Thanks!!

从表格示例 URL https://material.angular.io/components/table/examples 的文档站点导航开始，检查左侧菜单的呈现方式。确定搜索或筛选功能适合放置的位置，然后验证搜索“Spinner”是否会显示相关的组件选项，以及现有导航是否仍然可用。

由索引模型根据 Issue 内容生成。