fix(dev_manual): add a note about jQuery drop in Notifications app

Signed-off-by: Maksim Sukharev <antreesy.web@gmail.com>

developer_manual/app_publishing_maintenance/app_upgrade_guide/upgrade_to_31.rst

@@ -60,7 +60,15 @@ Removed APIs
 ^^^^^^^^^^^^
 
 - ``OCA.FilesSharingDrop`` removed as part of the Vue migration. Use the Files app API provided by the :ref:`package<js-library_nextcloud-files>` .
+- ``$.Event('OCA.Notification.Action')`` jQuery event removed from Notifications app as part of the Vue migration. Use ``@nextcloud/event-bus`` :ref:`package<js-library_nextcloud-event-bus>` instead.
 
+.. code-block:: JavaScript
+
+    import { subscribe, unsubscribe } from '@nextcloud/event-bus'
+
+    subscribe('notifications:action:execute', (event) => {
+		console.info('Notification action has been executed:', event.notification, event.action)
+    })
 
 Back-end changes
 ----------------

developer_manual/digging_deeper/javascript-apis.rst

@@ -55,6 +55,8 @@ This package provides information about the current user and session. Documentat
 
 This package provides an `Axios <https://www.npmjs.com/package/axios>`_ HTTP client instance, ready to send request to the Nextcloud server. If you use this instance you do not have to care about authentication and special headers. Documentation: https://nextcloud-libraries.github.io/nextcloud-axios/
 
+.. _js-library_nextcloud-event-bus:
+
 ``@nextcloud/event-bus``
 ^^^^^^^^^^^^^^^^^^^^^^^^