docs: add entry to update hosted zone id manually if any added

docs/add-a-new-region.md

@@ -56,3 +56,4 @@ Some data sources include static values specific to regions that are not availab
 - Check [Amazon Simple Storage Service endpoints and quotas](https://docs.aws.amazon.com/general/latest/gr/s3.html#s3_website_region_endpoints) and add Route53 Hosted Zone ID if available to [`internal/service/s3/hosted_zones.go`](https://github.com/hashicorp/terraform-provider-aws/tree/main/internal/service/s3/hosted_zones.go)
 - Check [AWS Elastic Beanstalk endpoints and quotas](https://docs.aws.amazon.com/general/latest/gr/elasticbeanstalk.html) and add Route53 Hosted Zone ID if available to [`internal/service/elasticbeanstalk/hosted_zone_data_source.go`](https://github.com/hashicorp/terraform-provider-aws/tree/main/internal/service/elasticbeanstalk/hosted_zone_data_source.go)
 - Check [SageMaker docs](https://docs.aws.amazon.com/sagemaker/latest/dg/sagemaker-algo-docker-registry-paths.html) and add AWS Account IDs if available to [`internal/service/sagemaker/prebuilt_ecr_image_data_source.go`](https://github.com/hashicorp/terraform-provider-aws/tree/main/internal/service/sagemaker/prebuilt_ecr_image_data_source.go)
+- Check [App Runner docs](https://docs.aws.amazon.com/general/latest/gr/apprunner.html#apprunner_region) and add Route53 Hosted Zone ID if available to [`internal/service/apprunner/hosted_zone_id_data_source.go`](https://github.com/hashicorp/terraform-provider-aws/tree/main/internal/service/apprunner/hosted_zone_id_data_source.go)