remove useless components level in doc

src/components/Charts/index.md

 ---
-category: Components
 type: General
 title: Charts
 subtitle: 图表

src/components/CountDown/index.md

 ---
-category: Components
 type: General
 title: CountDown 
 subtitle: 倒计时

src/components/DescriptionList/index.md

 ---
-category: Components
 type: General
 title: DescriptionList
 subtitle: 描述列表

src/components/Exception/index.md

 ---
-category: Components
 type: General
 title: Exception
 subtitle: 异常

src/components/FooterToolbar/index.md

 ---
-category: Components
 type: General
 title: FooterToolbar
 subtitle: 底部工具栏

src/components/GlobalFooter/index.md

 ---
-category: Components
 type: General
 title: GlobalFooter
 subtitle: 全局页脚

src/components/HeaderSearch/index.md

 ---
-category: Components
 type: General
 title: HeaderSearch
 subtitle: 顶部搜索框

src/components/NoticeIcon/index.md

 ---
-category: Components
 type: General
 title: NoticeIcon
 subtitle: 通知菜单

src/components/PageHeader/index.md

 ---
-category: Components
 type: General
 title: PageHeader 
 subtitle: 页头

src/components/Result/index.md

 ---
-category: Components
 type: General
 title: Result
 subtitle: 处理结果

src/components/TagSelect/index.md

 ---
-category: Components
 type: General
 title: TagSelect 
 subtitle: 标签选择器