docs: update readme

Author: benmonro

README.md

@@ -1,5 +1,6 @@
 # eslint-plugin-jest-dom
 [![Build Status](https://travis-ci.org/testing-library/eslint-plugin-jest-dom.svg?branch=master)](https://travis-ci.org/testing-library/eslint-plugin-jest-dom)
+[![version][version-badge]][package]
 [![All Contributors](https://img.shields.io/badge/all_contributors-3-orange.svg?style=flat-square)](#contributors)
 
 lint rules for use with [jest-dom](https://github.com/testing-library/jest-dom).
@@ -91,3 +92,6 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
 <!-- ALL-CONTRIBUTORS-LIST:END -->
 
 This project follows the [all-contributors](https://github.com/all-contributors/all-contributors) specification. Contributions of any kind welcome!
+
+[package]: https://www.npmjs.com/package/esling-plugin-jest-dom
+[version-badge]: https://img.shields.io/npm/v/eslint-plugin-jest-dom.svg?style=flat-square