Merge pull request #13485 from nextcloud/feat/developer/i-preloadable-notifier

feat(developer): add IPreloadableNotifier to upgrade guide

Author: st3iny

developer_manual/app_publishing_maintenance/app_upgrade_guide/upgrade_to_32.rst

@@ -70,6 +70,7 @@ Added APIs
 - New interface ``\OCP\OCM\ICapabilityAwareOCMProvider`` to extend the OCM provider with 1.1 and 1.2 extensions of the Open Cloud Mesh Discovery API
 - New task processing task type ``OCP\TaskProcessing\AnalyzeImages`` to ask questions about images.
 - New interface ``\OCP\Search\IExternalProvider`` allows extending the search provider with an explicit flag to indicate that the search is performed on external (3rd-party) resources. This is used in Unified Search to disable searches through these by default (via a toggle switch).
+- New interface ``\OCP\Notification\IPreloadableNotifier`` to allow notifier implementations to preload and cache data for many notifications at once to improve performance by, for example, bundling SQL queries.
 
 Changed APIs
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