Adds additional user attributes to the user pool schema.Show details from next link. https://docs.aws.amazon.com/ja_jp/cli/latest/reference/cognito-idp/add-custom-attributes.html
| aws cognito-idp add-custom-attributes --user-pool-id |
| ruby - Getting Around Terraform's Limitations - Stack Overflow : http://stackoverflow.com/questions/48945486/getting-around-terraforms-limitations |