Updates to the cheat sheet for the Octane launch

[jenweber]

Closes #18

Please let me know if anything is missing or confusing! The best way to review this is to look at the screenshot below or run this app locally.

Changed:

• replaced Avatar references 😭
• Moved "default properties" into the Component Properties section
• Replaced "Automation" links that went to codemods with links to the upgrade guide instead.

Added

• Section on mixins
• Section on generating element ids
• Link to the upgrade guides in the intro text
• Section on @model
• Section on component generators
• section on template co-location
• separate section on get and set
• section on DDAU

[jenweber]

This section is just moved from its previous (incorrect) location under Templates

[jenweber]

[MarcoUmpierrez]

This should be @answer={{42}}, right? at least that's what is suggested in ember-template-lint:

Attribute [attribute] should be either quoted or wrapped in mustaches

[jenweber]

Good catch, thank you!

[MarcoUmpierrez]

Also:

 @action
  helloWorld() {
    console.log('Hello, world!');
  }

  @action
  saySomethingElse(message) {
    console.log(message);
  }

these don't need the @action decorator because they aren't using the context of the component (as far as I know).

[pzuraq]

@MarcoUmpierrez it's generally best practice to mark methods used in templates with @action since they will likely use this at some point. I think it's better to keep the @action decorator.

[jenweber]

Hello everyone, thank you so much for the reviews! If you can think of anything else that will improve this cheat sheet, let me know :)