Fix missing MAX_DINNERS in example config

Change-Id: I76415bf01dcdd09d533bc22e1189201cca026fbf
diff --git a/config.php.example b/config.php.example
index 4f67a19..ce9345d 100755
--- a/config.php.example
+++ b/config.php.example
@@ -23,6 +23,7 @@
 $REGULAR_CONFERENCE_FEE = 280;
 $EARLYBIRD_CONFERENCE_FEE = 240;
 $CONFERENCE_DINNER = 60;
+$MAX_DINNERS = 90;
 $STUDENT_DISCOUNT = 80;
 $EXCURSION = 20;
 $EARLYBIRD_DEADLINE = "15 May 2023"; // HAWAIAN TIME (HST) is used :)