pm-4.1.x-dev/modules/pm_invoice/pm_invoice.links.menu.yml

entity.pm_invoice.collection:
  title: 'Invoice'
  route_name: entity.pm_invoice.collection
  parent: pm.admin.content_items
  description: ''
  weight: -15

entity.pm_invoice_type.collection:
  title: 'Invoice types'
  parent: pm.admin.content_settings
  route_name: entity.pm_invoice_type.collection
  weight: -14