upgrade/5.8.x-to-6.0.0.md: notes about app_python3 and dialog changes

docs/install/upgrade/5.8.x-to-6.0.0.md

@@ -30,11 +30,15 @@ Following tokens are used to mark the changes:
 
 ### Upgraded Modules
 
-- none
+-  **app_python3**
+  * removed legacy exported modules to Python, use instead the KEMI `KSR` modules
+
+- **dialog**
+  * dropped support for dlg_flag parameter
 
 ### Removed Modules
 
-- none
+- see the section about `Archived Modules`
 
 ### Renamed Modules