update docs

packages/artplayer-document/docs/en/Plugins/iframe.mdx

@@ -3,6 +3,12 @@ title: Iframe Plugin
 sidebar_position: 3
 ---
 
+## Overview
+
+With this plug-in, you can easily control the player in the `iframe` page in the `main page`.
+
+For example, you can control the functions of the `iframe` player through code in the `main page`, or get the value of the `iframe` player.
+
 ## Demo
 
 👉 [View Demo](https://artplayer.org/?libs=./uncompiled/artplayer-plugin-iframe/index.js&example=iframe)