fix(): comment emiteBeforeInitialize and migrate example app to vue3

Author: rieg-ec

example/src/main.js

@@ -1,9 +1,7 @@
-import Vue from 'vue'
-import App from './App.vue'
+import { createApp } from 'vue';
+import App from './App.vue';
 
-Vue.config.productionTip = true
-// Vue.config.ignoredElements = ['trix-editor']
+const app = createApp(App);
+app.mount('#app')
 
-new Vue({
-  render: h => h(App)
-}).$mount('#app')
+export default app;