Fix default export

Author: bcomnes

README.md

@@ -76,7 +76,7 @@ yarn add netlify-identity-widget
 Import or require as usual:
 
 ```js
-import netlifyIdentity from "netlify-identity-widget"
+const netlifyIdentity =  require("netlify-identity-widget")
 
 netlifyIdentity.init({
   container: "#netlify-modal" // defaults to document.body

webpack.config.babel.js

@@ -20,7 +20,8 @@ module.exports = {
     publicPath: "/",
     filename: "[name].js",
     library: "netlifyIdentity",
-    libraryTarget: "umd"
+    libraryTarget: "umd",
+    libraryExport: "default"
   },
 
   resolve: {