tutorial: add translation note

[ci skip]

(cherry-picked from commit 7a020c3130)

data/campaigns/tutorial/scenarios/01_Tutorial_part_1.cfg

@@ -938,6 +938,7 @@
             speaker=narrator
             caption= _ "Victory"
             image=wesnoth-icon.png
+            # po: linger mode is a term which is used nowhere else in the game, it's only relevant for writing scenarios. It makes no sense to come up with a localized version of it, nor to tell the player that there is an English term for it. Leave that part out in the translation of this text.
             message= _ "After your victory notice, the map will be grayed out to indicate that the scenario is over; this is called <i>linger mode</i>. You will still be able to examine the final positions and state of your troops and any surviving enemies. When you’re finished, click the <b>End Scenario</b> button to go on to the next scenario in the campaign."
         [/message]
     [/event]