fix: add note about Vue 2.7

Author: antfu

README.md

@@ -8,6 +8,9 @@ Vue 2 plugin for **Composition API**
 
 English | [中文](./README.zh-CN.md) ・ [**Composition API Docs**](https://v3.vuejs.org/guide/composition-api-introduction.html)
 
+
+> ⚠️ With the release of [Vue 2.7](https://blog.vuejs.org/posts/vue-2-7-naruto.html), which has Composition API built-in, **you no longer need this plugin**. Thereby this plugin has entered maintenance mode and will only support Vue 2.6 or earlier. This project will reach End of Life by the end of 2022.
+
 ## Installation
 
 ### NPM

README.zh-CN.md

@@ -7,6 +7,9 @@
 
 [English](./README.md) | 中文 ・ [**组合式 API 文档**](https://v3.cn.vuejs.org/guide/composition-api-introduction.html)
 
+
+> ⚠️ 随着 [Vue 2.7](https://blog.vuejs.org/posts/vue-2-7-naruto.html)的发布，它内置了Composition API，**你不再需要这个插件了**。因此，这个插件已经进入维护模式，将只支持Vue 2.6 或更早的版本。本项目将在 2022 年底达到生命终点（EOL）。
+
 ## 安装
 
 ### NPM

package.json

@@ -51,7 +51,7 @@
   },
   "homepage": "https://github.com/vuejs/composition-api#readme",
   "peerDependencies": {
-    "vue": ">= 2.5 < 3"
+    "vue": ">= 2.5 < 2.7"
   },
   "devDependencies": {
     "@rollup/plugin-node-resolve": "^13.3.0",