[css-ruby] Lift potential ambiguity on the order of annotation pairing

Author: frivoal

css-ruby-1/Overview.bs

@@ -486,7 +486,7 @@ Unit Pairing and Spanning Annotations</h4>
 	all of the [=ruby bases=] in its [=ruby segment=].
 
 	Otherwise, each [=ruby annotation=] is paired,
-	in order, with the corresponding [=ruby base=] in that segment.
+	in document order, with the corresponding [=ruby base=] in that segment.
 	If there are not enough [=ruby annotations=] in a [=ruby annotation container=],
 	the remaining [=ruby bases=] are paired with anonymous empty annotations
 	inserted at the end of the [=ruby annotation container=].