describing an endpoint to download files

/attachments/{id}:
  get:
    summary: download an attachment
    parameters:
      - in: path
        name: id
        required: true
        schema:
          type: integer
          format: int64
    responses:
      200:
        description: attachment data
        headers:
          Content-Disposition:
            schema:
              type: string
            description: the format is `attachment; filename="name.zip"`
        content:
          application/*:
            schema:
              type: string
              format: binary
          image/*:
            schema:
              type: string
              format: binary