[css-contain-3] Container query units in a query resolve like other relative units (#7410)

Author: mirisuzanne

css-contain-3/Overview.bs

@@ -759,7 +759,9 @@ Size Container Features</h3>
 	or the [=query container=] does not support [=container size queries=] on the relevant axes,
 	then the result of evaluating the [=size feature=] is unknown.
 
-	[=Relative length=] units in [=container query=] conditions
+	[=Relative length=] units
+	(including [=container query length=] units)
+	in [=container query=] conditions
 	are evaluated based on the the [=computed values=] of the [=query container=].
 
 	Note: This is different from the handling of relative units in [=media queries=].