content_entity_example.links.menu.yml

entity.content_entity_example_contact.collection:
  title: 'Content Entity Example'
  route_name: entity.content_entity_example_contact.collection
  description: 'List contacts'
content_entity_example_contact.admin.structure.settings:
  title: 'Contact settings'
  description: 'Configure contact entity'
  route_name: content_entity_example.contact_settings
  parent: system.admin_structure