Add copyright notice to interop-kms.yaml and update summary.

# Copyright 2022 ETSI

# Licensed under the BSD-3 Clause (https://forge.etsi.org/legal-matters)

openapi: '3.0.3'

info:

  title: Draft ETSI GS QKD 020 - Interoperable Key Management System API

paths:

  /kdapi/v2/ext_keys:

    post:

      summary: 'Transfer keys to external KMS'

      summary: 'Transfer keys to external KMS for delivery'

      tags:

      - 'Extended Specification'

      description: 'Pass an Extended Key Container comprising key material and associated data to another KME, for the key(s) to be delivered (by relay where necessary) to the target SAE(s) specified. The Extended Key Container contains keys matching those to be delivered to the initiator SAE.'