custom_tables_datasource.links.menu.yml

custom_tables_datasource.settings_form:
  title: 'Custom Tables Datasource'
  description: 'Configure Custom Tables Datasource.'
  parent: system.admin_config_search
  route_name: custom_tables_datasource.settings_form
  weight: 10
custom_tables_datasource.data_page:
  title: 'Custom Tables Datasource Data'
  description: 'See the data from Custom Tables Datasource.'
  parent: system.admin_config_search
  route_name: custom_tables_datasource.data_page
  weight: 11