[css-ruby-1] Clarify that we're talking about segment break transformation rules.

Author: fantasai

css-ruby-1/Overview.bs

@@ -630,7 +630,8 @@ White Space Collapsing</h3>
 	it will collapse across consecutive elements
 	following the standard <a href="https://www.w3.org/TR/css3-text/#white-space-rules">white space processing rules</a>. [[!CSS3TEXT]]
 	For [=collapsible white space=] between [=ruby segments=] ([=inter-segment white space=]), however,
-	the contextual text for determining collapsing behavior is given by the [=ruby bases=] on either side,
+	the contextual text for determining [[css-text-3#line-break-transform|segment break transformations]]
+	is given by the [=ruby bases=] on either side,
 	not the text on either side of the white space in source document order.
 
 	<div class="note">