examples-3.x-dev/modules/config_simple_example/config_simple_example.links.menu.yml

config_simple_example.description:
  title: 'Config Simple Example'
  description: 'Custom translatable config form'
  route_name: config_simple_example.description
  expanded: TRUE
config_simple_example.settings:
  title: 'Config Simple Example Settings'
  route_name: config_simple_example.settings
  parent: config_simple_example.description
  description: ''
  weight: -15