Include minimum quorum for AC appeal

part of #886

See https://www.w3.org/2024/07/15-ab-minutes.html#r02

index.bs

@@ -2845,7 +2845,9 @@ Advisory Committee Override</h3>
 	The level of support needed for a [=Advisory Committee Override=] to pass
 	depends on the level of participation by [=Advisory Committee Representatives=],
 	(including those who cast an explicit “abstain” ballot):
-	* if 15% or fewer participate,
+	* if fewer than 5% participate,
+		the vote fails.
+	* if at least 5% but no more than 15% participate,
 		and the number of “Approve” ballots exceeds three times (3x) the number of “Reject” ballots,
 		the vote passes.
 	* if more than 15% but fewer than 20% participate,