more rephrase changelog

Author: adutra

CHANGELOG.md

@@ -34,7 +34,7 @@ request adding CHANGELOG notes for breaking (!) changes and possibly other secti
 - Event listeners are now executed on a dedicated executor. **This executor does not propagate the original request's CDI context**; listeners that were improperly relying on that should instead manage their own CDI request scope from now on. Furthermore, two new configuration options were introduced to configure the executor: 
   - `polaris.event-listener.executor.pool-size` configures the thread pool size.
   - `polaris.event-listener.executor.queue-size` configures the queue size for pending events when all threads are busy.
-- The Helm chart now includes a new `persistence.relationalJdbc.datasource` option to select the relational database to activate. The default is `postgresql`.
+- The Helm chart now includes a new `persistence.relationalJdbc.datasource` option to select the relational database to activate. The default is `postgresql`, which matches pre-existing behavior.
 
 ### Breaking changes
 - The `MaintenanceService.performMaintenance()` signature now requires an explicit `OptionalLong overrideRunId` argument to supersede the latest unfinished maintenance run.
@@ -44,6 +44,7 @@ request adding CHANGELOG notes for breaking (!) changes and possibly other secti
     - Names containing control (invisible) characters
     - Names with leading or trailing whitespace
     - Names containing any of these characters: <code>/\:*?"<>|#+`</code>
+- Due to the introduction of dynamic datasource activation, the default (PostgreSQL) datasource is now unused. If you had any custom configuration for that datasource, it should be migrated from `quarkus.datasource.*` to `quarkus.datasource.postgresql.*`. The same is valid for environment variables: `QUARKUS_DATASOURCE_*` should be replaced with `QUARKUS_DATASOURCE_POSTGRESQL_*`.
 
 ### New Features
 - Added `SESSION_NAME_FIELDS_IN_SUBSCOPED_CREDENTIAL` feature flag for AWS credential vending. Operators can now configure an ordered list of fields (`realm`, `catalog`, `namespace`, `table`, `principal`) to compose structured STS role session names (e.g. `p-acme-hr_catalog-employee-etl_writer`). Session names are sanitized and proportionally truncated to the AWS 64-character limit. When unset, existing `INCLUDE_PRINCIPAL_NAME_IN_SUBSCOPED_CREDENTIAL` behaviour is preserved.