[OCTANE] Update component-basics

[Frozenfire92]

This PR updates the route /release/components/component-basics for #588

Summary

• switch to using {{action this.sayHello}} instead of onclick={{this.sayHello}} as outlined in: Review and Octanify the template guides #598 (comment)
• change code fences to ```handlebars and ```javascript
• correct action import
• add component usage filenames of application template
• update example code with CustomButton to be simpler and more consistent with other sections of the guides (Icon component instead, consistent argument usage)
• fix yield helper reference
• add mention of Interacting with the DOM to the further guides footnote. Assuming this is the correct section name as mentioned in: Octane guides: Component section (tracking issue) #395 (comment)

Remaining work

• comment: [TODO: Screenshot of the Component tree in the Ember Inspector] depends on Ember Octane support emberjs/ember-inspector#931

[Frozenfire92]

Question:

I noticed when generating components within an octane blueprint app (ember new my-app -b @ember/octane-app-blueprint)

they add Component to the end of the class name, like so:

export default class HelloButtonComponent extends Component {

is this going to be like the case when octane releases? if so we should likely update this example to have Component on the end of the class name as well

[mike-north]

if so we should likely update this example to have Component on the end of the class name as well

I'd go beyond this and ask that code snippets in the guides match exactly what readers will see/experience as they follow along.

[jenweber]

Looks good to go! I would like to merge this after #638, since I think it's MVP.