rename demo example into benchmarks

examples/benchmarks/main.js

@@ -0,0 +1,13 @@
+import { App } from "./app.js";
+
+function createApp(el) {
+  const env = {
+    qweb: new odoo.core.QWeb()
+  };
+  const app = new App(env, { initialState: 13 });
+  app.mount(el);
+}
+
+document.addEventListener("DOMContentLoaded", function() {
+  createApp(document.body);
+});