docs(route53resolver-alpha): fix typos (#32915)

### Issue # (if applicable)

None

### Reason for this change

Fixed typos in code comments.

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

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*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-route53resolver-alpha/lib/firewall-rule-group-association.ts

@@ -80,7 +80,7 @@ export class FirewallRuleGroupAssociation extends Resource {
 
   /**
    * The owner of the association, used only for lists that are not managed by you.
-   * If you use AWS Firewall Manager to manage your firewallls from DNS Firewall,
+   * If you use AWS Firewall Manager to manage your firewalls from DNS Firewall,
    * then this reports Firewall Manager as the managed owner.
    * @attribute
    */