docs(tabbar): add import Icon (#1028)

* docs(tabbar): add import Icon #1002

src/packages/__VUE/tabbar/doc.md

@@ -8,9 +8,9 @@
 ``` javascript
 import { createApp } from 'vue';
 //vue
-import { Tabbar,TabbarItem } from '@nutui/nutui';
+import { Tabbar,TabbarItem,Icon } from '@nutui/nutui';
 //taro
-import { Tabbar,TabbarItem } from '@nutui/nutui-taro';
+import { Tabbar,TabbarItem,Icon } from '@nutui/nutui-taro';
 
 const app = createApp();
 app.use(Tabbar);