GameUI: improve comment regarding parked autocomplete suggest position

Make sure this doesn't get confused with out of screen while still indexing into the list.

src/gameui/IConsole.h

@@ -69,7 +69,8 @@ private: // Internals.
 private:
     enum ConAutoCompletePos_e
     {
-        // Park means the position is out of screen.
+        // Park means the auto complete position is out of screen and not
+        // indexing an item.
         kPark = -1,
     };