Fix invalid main field (#12)

package.json

@@ -2,7 +2,7 @@
   "name": "driver.js",
   "version": "0.1.6",
   "description": "A light-weight, no-dependency, vanilla JavaScript library to drive the user's focus across the page",
-  "main": "./assets/scripts/dist/driver.min.js",
+  "main": "dist/driver.min.js",
   "scripts": {
     "start": "node server.js",
     "build": "webpack --config webpack.config.prod.js"