update unused key list

src/game/boe.actions.cpp

@@ -2387,7 +2387,7 @@ void show_debug_help() {
 }
 
 // Non-comprehensive list of unused keys:
-// UYZ chijklnoqvy @#$-_+[]{},.'"`~/\|;:
+// Y chijklnoqvy @#$-_+[]{},.'"`~/\|;:
 void init_debug_actions() {
 	add_debug_action({'B'}, "Leave town", debug_leave_town);
 	add_debug_action({'C'}, "Get cleaned up (lose negative status effects)", debug_clean_up);