commerce-8.x-2.8/modules/payment/commerce_payment.links.menu.yml

commerce_payment.configuration:
  title: 'Payment'
  route_name: 'commerce_payment.configuration'
  parent: 'commerce.configuration'
  weight: -10

entity.commerce_payment_gateway.collection:
  title: 'Payment gateways'
  route_name: 'entity.commerce_payment_gateway.collection'
  parent: 'commerce_payment.configuration'
  description: 'Configure the gateways you take payment through.'