Document ember-cli Addon Hooks

We don't have a clear and easy way to learn ember-cli hooks even for experienced Ember.js developers sometimes we have to jump into the ember-cli [codebase](https://github.com/ember-cli/ember-cli/blob/bd052719e76a9d15be7a7f2e20fa1b2c082a3700/lib/models/addon.js) to understand many points about the hooks:

I'd love to see these hooks very well documented into CLI Guides. How can we start this initiative @jenweber @locks to make our guides better?

https://ember-cli.com/api/classes/addon