[css-multicol] Updates pseudo-algorithm

column-height now also creates a multicol container.

Author: rachelandrew

css-multicol-2/Overview.bs

@@ -1050,7 +1050,7 @@ Two assumptions are being made by the pseudo-algorithm:
 	The <code>floor(X)</code> function returns the largest integer Y &le; X.
 
 	<pre>
-	(01)  if ((column-width = auto) and (column-count = auto)) then
+	(01)  if ((column-width = auto) and (column-count = auto) and (column-height = auto)) then
 	(02)      exit; /* not a multicol container */
 	(03)  if column-width = auto then
 	(04)      N := column-count