MDL-49290 message: add note about removed function

message/upgrade.txt

@@ -3,6 +3,7 @@ information provided here is intended especially for developers.
 
 === 3.1 ===
 * get_message_processors accepts an addition parameter for testing, which will just reset processor and exit.
+* Deprecated method message_current_user_is_involved() has been removed.
 
 === 2.9 ===
 * Renderer method \core_message_renderer::manage_messagingoptions now accepts a user id parameter as well.