Removed the package badge from README

Because it doesn't seem to update despite the release. I'm not going to push another NPM version just to remove it from the readme shown on NPM, but it most likely won't be in future versions.

README.md

@@ -1,6 +1,6 @@
 # Webpack Plugin: Three
 
-[![Build Status](https://travis-ci.com/wildpeaks/package-three-webpack-plugin.svg?branch=master)](https://travis-ci.com/wildpeaks/package-three-webpack-plugin) [![Known Vulnerabilities](https://snyk.io/test/github/wildpeaks/package-three-webpack-plugin/badge.svg?targetFile=package.json)](https://snyk.io/test/github/wildpeaks/package-three-webpack-plugin?targetFile=package.json) [![Greenkeeper badge](https://badges.greenkeeper.io/wildpeaks/package-three-webpack-plugin.svg)](https://greenkeeper.io/) [![npm version](https://badge.fury.io/js/%40wildpeaks%2Fthree-webpack-plugin.svg)](https://www.npmjs.com/package/@wildpeaks/three-webpack-plugin)
+[![Build Status](https://travis-ci.com/wildpeaks/package-three-webpack-plugin.svg?branch=master)](https://travis-ci.com/wildpeaks/package-three-webpack-plugin) [![Known Vulnerabilities](https://snyk.io/test/github/wildpeaks/package-three-webpack-plugin/badge.svg?targetFile=package.json)](https://snyk.io/test/github/wildpeaks/package-three-webpack-plugin?targetFile=package.json) [![Greenkeeper badge](https://badges.greenkeeper.io/wildpeaks/package-three-webpack-plugin.svg)](https://greenkeeper.io/)
 
 Webpack plugin to use the additional **[Three.js](https://threejs.org/) "examples" classes that aren't ES Modules**,
 such as [THREE.OrbitControls](https://threejs.org/docs/index.html#examples/controls/OrbitControls).