[css-sizing-4] Clarify that transfers are bidirectional. w3c@ede56bd#r40633182

Author: fantasai

css-sizing-4/Overview.bs

@@ -216,7 +216,7 @@ Intrinsic Aspect Ratios: the 'aspect-ratio' property</h3>
 	at least one of these sizes must be ''width/auto'' (/''flex-basis/content'')
 	for the <a>preferred aspect ratio</a> to have an impact on sizing.
 
-	Additionally, sizing constraints in an axis
+	Additionally, sizing constraints in either axis
 	(the <var>origin</var> axis)
 	are transferred through the [=preferred aspect ratio=]
 	to the other axis (the <var>destination</var> axis)