Update README

[atdrago]

The README examples could use some updates:

• New methods of referencing Electron modules (e.g., const { app } = require('electron') instead of const app = require('app'))
• Usage of ES6 syntax
  • const and let instead of var
  • arrow functions
  • destructuring assignment

Let me know what you think of this. I can do it at some point. Just wanted to write it down so I remember. :)

[jprichardson]

This would be awesome, PR accepted :) Thanks!