pbek/qownnotesapi#49 doc: update changelog

Signed-off-by: Patrizio Bekerle <patrizio@bekerle.com>

CHANGELOG.md

@@ -4,6 +4,11 @@
 - The QOwnNotes API <https://api.qownnotes.org> got migrated to PHP 8.2,
   Symfony 6.4 and API Platform 3.3  for more speed and to be more future-proof
   (for [#11](https://github.com/qownnotes/api/issues/11))
+- The QOwnNotesAPI Nextcloud app was enabled and tested app for Nextcloud 30
+  (for [#49](https://github.com/pbek/qownnotesapi/issues/49))
+  - There were troubles with the version API that didn't always happen when trying to access the versions of a file:
+    `Call to a member function getOwner() on null in file '/var/www/html/lib/private/Files/Filesystem.php' line 728`
+    - It's unclear why this happens, but it seems to be a problem with the Nextcloud server and not the app
 
 ## 24.9.6
 - The accidental note selection when selecting a note subfolder in the experimental