docs(acm): fix link text for exportable certificates documentation (#38971)

### Issue # (if applicable)

Closes #38970.

### Reason for this change

In the `aws-certificatemanager` README, the section "Requesting public SSL/TLS certificates exportable to use anywhere" links to the exportable public certificates guide, but the link text reads "opting out of certificate transparency logging". The text was copied from the following section and does not describe the linked page. This was introduced in #35079.

### Description of changes

Change the link text to "AWS Certificate Manager exportable public certificates", the title of the linked page. The URL is unchanged.

### Describe any new or updated permissions being added

N/A

### Description of how you validated changes

Documentation only. Verified that the link points to the exportable public certificates page of the ACM User Guide and that the new text matches its title.

### 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)

----

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

Author: frankhefeng

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

@@ -148,7 +148,7 @@ new acm.PrivateCertificate(this, 'PrivateCertificate', {
 
 ## Requesting public SSL/TLS certificates exportable to use anywhere
 
-AWS Certificate Manager can issue an exportable public certificate. There is a charge at certificate issuance and again when the certificate renews. See [opting out of certificate transparency logging](https://docs.aws.amazon.com/acm/latest/userguide/acm-exportable-certificates.html) for details.
+AWS Certificate Manager can issue an exportable public certificate. There is a charge at certificate issuance and again when the certificate renews. See [AWS Certificate Manager exportable public certificates](https://docs.aws.amazon.com/acm/latest/userguide/acm-exportable-certificates.html) for details.
 
 ```ts
 new acm.Certificate(this, 'Certificate', {