chore: link to provider_meta docs in changelog entry

Author: jar-b

.changelog/45464.txt

@@ -1,5 +1,5 @@
 ```release-note:enhancement
-provider: The `provider_meta` block is now supported. The `user_agent` argument enables module authors to include additional product information in the `User-Agent` header sent during all AWS API requests made during Create, Read, Update, and Delete operations.
+provider: The [`provider_meta` block](https://developer.hashicorp.com/terraform/internals/provider-meta) is now supported. The `user_agent` argument enables module authors to include additional product information in the `User-Agent` header sent during all AWS API requests made during Create, Read, Update, and Delete operations.
 ```
 ```release-note:enhancement
 provider: Add `user_agent` argument