add missing rollup.config.js from template

rollup.config.js

@@ -0,0 +1,16 @@
+import json from "rollup-plugin-json";
+import cleanup from "rollup-plugin-cleanup";
+import executable from "rollup-plugin-executable";
+import resolve from "rollup-plugin-node-resolve";
+import commonjs from "rollup-plugin-commonjs";
+import pkg from "./package.json";
+
+export default {
+  plugins: [resolve(), commonjs()],
+  input: pkg.module,
+  output: {
+    file: pkg.main,
+    format: "cjs",
+    interop: false
+  }
+};