feat: added an example to use api

Author: NataliaTepluhina

src/api/application-api.md

@@ -303,4 +303,17 @@ setTimeout(() => app.unmount(), 5000)
 
   When this method is called on the same plugin multiple times, the plugin will be installed only once.
 
+- **Example:**
+
+```js
+import { createApp } from 'vue'
+import MyPlugin from './plugins/MyPlugin'
+
+const app = createApp({})
+const i18nStrings = {
+
+app.use(MyPlugin)
+app.mount('#app')
+```
+
 - **See also:** [Plugins](../guide/plugins.html)