Broaden who may propose group closure

Addresses w3c#653

index.bs

@@ -1947,8 +1947,9 @@ Chartered Group Closure</h3>
 	A [=Working Group=] or [=Interest Group=] charter specifies a duration for the group.
 
 	In exceptional circumstances,
-	The [=Team=] <em class="rfc2119">may</em> propose through an [=AC Review=]
+	The [=Team=], [=TAG=], or [=AB=] <em class="rfc2119">may</em> propose
 	to close a group prior to the date specified in the charter.
+	Any such proposal <em class=rfc2119>must</em> be subject to an [=AC Review=].
 	This may occur for instance
 	when a [=Patent Advisory Group=] concluded that the work <em class="rfc2119">should</em> be terminated.