Update change log.

laravel/documentation/changes.md

@@ -65,6 +65,7 @@
 - Allow the registration of custom cache and session drivers.
 - Allow the specification of a separate asset base URL for using CDNs.
 - Allow a `starter` Closure to be defined in `bundles.php` to be run on Bundle::start.
+- Allow the registration of custom database drivers.
 
 <a name="upgrade-3.2"></a>
 ## Upgrading From 3.1