find() method for nested resources

If you need to get a nested resource, without getting the parent model at first, you can do something like this.

// GET /users/1/posts

let User = new User({id: 1})
let Post = await User.posts().get()

// GET /users/1/posts/2
let User = new User({id: 1})
let Post = await User.posts().find(2)