invoicemgmt-1.0.0/invoicemgmt.routing.yml

invoicemgmt.settings:
  path: '/admin/config/invoicemgmt/settings'
  defaults:
    _form: '\Drupal\invoicemgmt\Form\InvoiceMgmtSettingsForm'
    _title: 'Invoice Management Settings'
  requirements:
    _permission: 'administer invoice management settings'