doc: remove subtitle in en-Us

src/components/HeaderSearch/index.en-US.md

@@ -1,6 +1,6 @@
 ---
 title: HeaderSearch
-subtitle: Top search box
+subtitle:
 cols: 1
 order: 8
 ---

src/components/NoticeIcon/index.en-US.md

@@ -1,6 +1,6 @@
 ---
 title: NoticeIcon
-subtitle: Notification Menu
+subtitle: 
 cols: 1
 order: 9
 ---