docs: Add needed resolve moethod to the documentation

Author: xiCO2k

README.md

@@ -9,7 +9,9 @@ import { createApp } from 'vue'
 import { i18nVue } from 'laravel-vue-i18n'
 
 createApp()
-    .use(i18nVue)
+    .use(i18nVue, {
+        resolve: lang => import(`../lang/${lang}.json`)
+    })
     .mount(document.getElementById('app'));
 ```