chore: add download badge (#8550) [ci skip]

README.md

@@ -1,4 +1,4 @@
-# vuejs/core [![npm](https://img.shields.io/npm/v/vue.svg)](https://www.npmjs.com/package/vue) [![build status](https://github.com/vuejs/core/actions/workflows/ci.yml/badge.svg?branch=main)](https://github.com/vuejs/core/actions/workflows/ci.yml)
+# vuejs/core [![npm](https://img.shields.io/npm/v/vue.svg)](https://www.npmjs.com/package/vue) [![build status](https://github.com/vuejs/core/actions/workflows/ci.yml/badge.svg?branch=main)](https://github.com/vuejs/core/actions/workflows/ci.yml) [![Download](https://img.shields.io/npm/dm/vue)](https://www.npmjs.com/package/vue)
 
 ## Getting Started