update readme

Author: badmintoncryer

packages/aws-cdk-lib/aws-rds/README.md

@@ -418,7 +418,7 @@ To apply changes of the cluster, such as engine version, in the next scheduled m
 
 For details, see [Modifying an Amazon Aurora DB cluster](https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/Aurora.Modifying.html).
 
-### Deleting Automated Backups
+### Retaining Automated Backups
 
 By default, when a database cluster is deleted, automated backups are removed immediately unless an AWS Backup policy specifies a point-in-time restore rule. You can control this behavior using the `deleteAutomatedBackups` property:
 
@@ -433,7 +433,8 @@ new rds.DatabaseCluster(this, 'Database', {
 });
 ```
 
-When set to `false`, automated backups are retained after the cluster is deleted. When set to `true` or not specified (default), automated backups are deleted immediately when the cluster is deleted.
+When set to `false`, automated backups are retained according to the configured retention period after the cluster is deleted. When set to `true` or not specified (default), automated backups are deleted immediately when the cluster is deleted.
+Detail about this feature can be found in the [AWS documentation](https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/Aurora.Managing.Backups.Retaining.html).
 
 ### Migrating from instanceProps