Creates an association between a direct connect gateway and a virtualprivate gateway (VGW).Show details from next link. https://docs.aws.amazon.com/ja_jp/cli/latest/reference/directconnect/create-direct-connect-gateway-association.html
| aws directconnect create-direct-connect-gateway-association --direct-connect-gateway-id 5f294f92-bafb-4011-916d-9b0bexample --virtual-gateway-id vgw-6efe725e |
| describe-direct-connect-gateway-attachments — AWS CLI 1.16.6 Command Reference : http://docs.aws.amazon.com/cli/latest/reference/directconnect/create-direct-connect-gateway-association.html |