update api.txt

api.txt

@@ -303,7 +303,7 @@ enhance mob functionality and have them do many interesting things:
 
    'on_rightclick'  its same as in minetest.register_entity()
    'on_blast'       is called when an explosion happens near mob when using TNT
-                    functions, parameters are (object, damage) and returns
+                    functions, parameters are (damage) and returns
                     (do_damage, do_knockback, drops)
    'on_spawn'       is a custom function that runs on mob spawn with 'self' as
                     variable, return true at end of function to run only once.