Add examples/documentation for closures

examples/closures/webpack.config.js

@@ -0,0 +1,10 @@
+const path = require('path');
+
+module.exports = {
+  entry: "./index.js",
+  output: {
+    path: path.resolve(__dirname, "dist"),
+    filename: "index.js",
+  },
+  mode: "development"
+};