docs: add a compatibility notice

README.md

@@ -106,6 +106,12 @@ This module is composed of several submodules and each of which can be used inde
 - [securityhub-baseline](./modules/securityhub-baseline)
 - [vpc-baseline](./modules/vpc-baseline)
 
+## Compatibility
+
+- Starting from v1.0, this module requires [Terraform Provider for AWS](https://github.com/terraform-providers/terraform-provider-aws) v4.0 or later. [Version 1.0 Upgrade Guide](./docs/upgrade-1.0.md) described the recommended procedure after the upgrade.
+- Starting from v0.20, this module requires [Terraform Provider for AWS](https://github.com/terraform-providers/terraform-provider-aws) v3.0 or later. Please use v0.19 if you need to use v2.x or earlier.
+- Starting from v0.10, this module requires Terraform v0.12 or later. Please use v0.9 if you need to use Terraform v0.11 or ealier.
+
 <!-- BEGINNING OF PRE-COMMIT-TERRAFORM DOCS HOOK -->
 ## Requirements
 
@@ -245,11 +251,6 @@ This module is composed of several submodules and each of which can be used inde
 | <a name="output_vpc_flow_logs_iam_role"></a> [vpc\_flow\_logs\_iam\_role](#output\_vpc\_flow\_logs\_iam\_role) | The IAM role used for delivering VPC Flow Logs to CloudWatch Logs. |
 <!-- END OF PRE-COMMIT-TERRAFORM DOCS HOOK -->
 
-## Compatibility
-
-- Starting from v0.20, this module requires [Terraform Provider for AWS](https://github.com/terraform-providers/terraform-provider-aws) v3.0 or later. Please use v0.19 if you need to use v2.x or earlier.
-- Starting from v0.10, this module requires Terraform v0.12 or later. Please use v0.9 if you need to use Terraform v0.11 or ealier.
-
 [cis amazon web services foundations v1.4.0]: https://www.cisecurity.org/benchmark/amazon_web_services/
 [aws foundational security best practices v1.0.0]: https://docs.aws.amazon.com/securityhub/latest/userguide/securityhub-standards-fsbp.html
 [providers within modules - terraform docs]: https://www.terraform.io/docs/modules/usage.html#providers-within-modules