Require decision by both the facilitator and team to abandon chartering

See w3c#982

index.bs

@@ -1775,7 +1775,7 @@ Charter Refinement</h3>
 	The [=charter refinement=] phase concludes when there is either:
 	* A [=group decision=] or [=Team Decision=] to initiate [=AC Review=] of the [=charter draft=],
 		subject to [=Team=] verification that the expectations of [=charter refinement=] are fulfilled.
-	* A [=chair decision=] by the [=Chartering Facilitator=] to abandon the proposal.
+	* A [=chair decision=] by the [=Chartering Facilitator=], confirmed by a [=Team Decision=], to abandon the proposal.
 
 	Any [=Formal Objection=] filed during the  [=charter refinement=] phase--
 	other than an objection to the choice of [=Chartering Facilitator=]