[migration] Updates Release Notes

ReleaseNotes.md

@@ -10,6 +10,7 @@
 - cta/CTA#1042 Do not iterate over retrieve queues when holding global scheduler lock
   - Repacks on a disabled tape must now use a mount policy whose name starts with repack
   - There is no longer an empty mount when a disabled/broken tape queue is full of deleted requests
+- Migration tools: fixes filemode of files imported from CASTOR to EOS
 
 # v4.3-1