Drupal 8 - The Entity CMS | Mediacurrent
This entity exists as a content entity with fields and full sets of storage, but relies on a newly created hook, hook_admin_config_BUNDLE, to create the field storage, config, form, and view displays. This custom entity would be useful in a case where we’d want to programmatically provide fields for bundle content implementations, like in the case of a custom admin menu with custom fields for storing globals such as images and text.