Change Quickstart JavaScript code blocks to use Class Syntax

[jenweber]

We'd love to have a volunteer for this! Please see Octane MVP for instructions about where to make your PR. Please only volunteer for this issue if you can open a PR by the end of the next day. Thanks for your help!

To-do

For this issue, we should only make "class syntax" changes to the code blocks within guides/release/getting-started markdown files. Later PRs will fix up the written explanations to go with them. Here's an example of converting to Class syntax:

// Before
import Controller from '@ember/controller';

export default Controller.extend({
  title: 'hello-world.app',
});

// After
import Controller from '@ember/controller';

export default class ApplicationController extends Controller {
  title = 'hello-world.app';
}

• branch from the octane branch of the guides
• See this guide's Native Classes explanation to learn about the changes you will have to make
• Make changes to the code blocks to use class syntax
• PR to the octane branch

[rajasegar]

I am working on it , raised a PR for the same, please let me know for anything.

[MelSumner]

Thank you @rajasegar for your work! 👍