message: chore(readme): correct badge link
diff: <p align="center"><a href="https://vuejs.org" target="_blank" rel="noopener noreferrer"><img width="100" src="https://vuejs.org/images/logo.png" alt="Vue logo"></a></p>
  <p align="center">
  - <a href="https://circleci.com/gh/vuejs/vue/tree/dev"><img src="https://img.shields.io/circleci/project/vuejs/vue/dev.svg" alt="Build Status"></a>
  + <a href="https://circleci.com/gh/vuejs/vue/tree/dev"><img src="https://img.shields.io/circleci/project/github/vuejs/vue/dev.svg" alt="Build Status"></a>
  <a href="https://codecov.io/github/vuejs/vue?branch=dev"><img src="https://img.shields.io/codecov/c/github/vuejs/vue/dev.svg" alt="Coverage Status"></a>
  <a href="https://npmcharts.com/compare/vue?minimal=true"><img src="https://img.shields.io/npm/dm/vue.svg" alt="Downloads"></a>
  <a href="https://www.npmjs.com/package/vue"><img src="https://img.shields.io/npm/v/vue.svg" alt="Version"></a>
  