docs: deprecated note

Akryum · web-flow · commit cee661fe5940 · 2018-07-12T14:39:38.000+02:00
diff --git a/README.md b/README.md
@@ -1,5 +1,7 @@
 # vue-cli [![Build Status](https://img.shields.io/circleci/project/vuejs/vue-cli/master.svg)](https://circleci.com/gh/vuejs/vue-cli) [![npm package](https://img.shields.io/npm/v/vue-cli.svg)](https://www.npmjs.com/package/vue-cli)
 
+**:warning: `vue-cli` is deprecated, see the [new documentation](https://cli.vuejs.org/guide/).**
+
 A simple CLI for scaffolding Vue.js projects.
 
 ### Installation
