make main process example shorter

docs/api/remote.md

@@ -159,11 +159,7 @@ project/
 ```js
 // main process: main/index.js
 const { app } = require('electron')
-app.on('ready', () => {
-
-// ...
-
-})
+app.on('ready', () => {/* ... */})
 ```
 
 ```js