add code inspector badge

Author: eidng8

README.md

@@ -3,6 +3,7 @@
 [![Master Build](https://travis-ci.com/eidng8/vue-tree.svg?branch=master)](https://travis-ci.com/eidng8/vue-tree)
 [![Master Coverage](https://coveralls.io/repos/github/eidng8/vue-tree/badge.svg?branch=master)](https://coveralls.io/github/eidng8/vue-tree?branch=master)
 [![Known Vulnerabilities](https://snyk.io/test/github/eidng8/vue-tree/badge.svg?targetFile=package.json)](https://snyk.io/test/github/eidng8/vue-tree?targetFile=package.json)
+[![Code Quality](https://www.code-inspector.com/project/5944/score/svg)](https://frontend.code-inspector.com/project/5944/dashboard)
 
 A Vue.js tree view component with stable DOM tree. By stable, it means the
 DOM structure will not change once it is rendered.