This commit intends to clarify the scope of ActionView::RecordIdentifier
methods `dom_id` and `dom_class`.
Most of the current documentation comes from da257eb8 (7 years ago) when
the decoupling of ActionView, ActiveRecord and ActiveModel was not a concern.
Since then, steps have been taken to reach such decoupling, especially
8ca17926 which duplicated ActionController::ModelNaming into
ActionView::ModelNaming explaining that:
> These are just a simple helpers for decoupling Active Model, so it does not
> make sense to extract it to Active Support, but the point is to decouple also
> Action View and Action Pack
As of today, ActionView::RecordIdentifier only includes `dom_id` and `dom_class`
so it makes sense to explicitly document those two methods, and leaving the
details of helpers like `div_for` in the corresponding files.
Moreover, I think it's important to mention in the documentation that
ActionView::RecordIdentifier **does not strictly depend on the ActiveRecord API**: any class `Post` implementing `post.to_key` and `post.model_name.param_key` will work.
[ci skip]
