[css-ruby] Use direction on annotation containers for merged annotations

Author: frivoal

css-ruby-1/Overview.bs

@@ -978,11 +978,15 @@ Bidi Reordering</h3>
 			by the 'direction' property of their [=ruby container=].
 		<li>
 			Within a segment, [=ruby bases=] and [=ruby annotations=]
+			that are not [=merged=]
 			are ordered within their respective containers
 			by the 'direction' property of the segment’s [=ruby base container=].
+			[=Merged annotations=] are ordered
+			by the 'direction' property of their [=annotation container=],
+			exactly as if they were a sequence of inline boxes within their [=annotation container=].
 
 			Note: This means the 'direction' property on [=ruby annotation containers=]
-			is ignored for the purpose of layout.
+			is ignored for the purpose of layout of non-[=merged=] annotations.
 			However, it can still inherit into the container's children
 			and thereby affect the [=inline base direction=]
 			of any [=ruby annotations=] it contains.