Update UPGRADE.md

Author: mac-cain13

UPGRADE.md

@@ -10,4 +10,9 @@ Since `ContainerAwareInterface` has been deprecated in Symfony 6.4, programmers
 
 Therefore, it makes no sense to keep `EndlessContainerAwareCommand`. If you need to call `EntityManager::clear()` on your doctrine instance inside `EndlessCommand::finishIteration()`, you have to handle this in your code now.
 
-If you need to access any service, inject it in the constructor of your derived class.
+If you need to access any service, inject it in the constructor of your derived class.
+
+### Other behaviour changes
+
+- Shutting down during startup will NOT run any iteration of the loop, previous versions did always at least run one iteration.
+- Support for using `setCode` to provide an implementation is removed.