Document relation views & usecases

[abrthel]

doc_page: core/relations

Relation views have basic documentation but only of simple examples. Documentation should include some advanced usecase examples to better flesh out the power of the feature.

Example Usecases

has_one through belongs_to

By default, not supported but can be implemented via

has_one :user, override: true, view: :for_comments

and a view Users#for_comments