chore(rds): fix typo in error message. (#21927)

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Author: jsphwllng

packages/@aws-cdk/aws-rds/lib/cluster.ts

@@ -738,7 +738,7 @@ export class DatabaseClusterFromSnapshot extends DatabaseClusterNew {
       Annotations.of(this).addWarning('Use `snapshotCredentials` to modify password of a cluster created from a snapshot.');
     }
     if (!props.credentials && !props.snapshotCredentials) {
-      Annotations.of(this).addWarning('Generated credentials will not be applied to cluster. Use `snapshotCredentials` instead. `addRotationSingleUser()` and `addRotationMultiUser()` cannot be used on tbis cluster.');
+      Annotations.of(this).addWarning('Generated credentials will not be applied to cluster. Use `snapshotCredentials` instead. `addRotationSingleUser()` and `addRotationMultiUser()` cannot be used on this cluster.');
     }
     const deprecatedCredentials = renderCredentials(this, props.engine, props.credentials);