docs: fix PageHeader demo with new Icon

components/page-header/demo/content.md

@@ -14,7 +14,8 @@ title:
 Show all props.Used all the capabilities provided by pageHeader.
 
 ```jsx
-import { PageHeader, Menu, Dropdown, Icon, Button, Tag, Typography, Row } from 'antd';
+import { PageHeader, Menu, Dropdown, Button, Tag, Typography, Row } from 'antd';
+import { Ellipsis } from '@ant-design/icons';
 
 const { Paragraph } = Typography;
 
@@ -47,8 +48,7 @@ const DropdownMenu = () => {
           padding: 0,
         }}
       >
-        <Icon
-          type="ellipsis"
+        <Ellipsis
           style={{
             fontSize: 20,
             verticalAlign: 'top',