Creating a new content entity in an existing enabled module

README.md

Let's say you just generated a content entity with drush:

drush generate entity:content

(... you go through the prompts, and the entity is created in an existing, enabled module)

In the module's .install file, add a hook_update_N(), for example if you previously called your entity a_super_cool_entity

/**
 * Install new entity type called a_super_cool_entity
 */
function backstopjs_tools_update_8001() {
  // Install the new a_super_cool_entity entity type.
  $update_manager = \Drupal::entityDefinitionUpdateManager();
  $update_manager->installEntityType(\Drupal::entityTypeManager()->getDefinition('a_super_cool_entity'));

}

And run drush updb