[css-ruby] Add reference to css-text for details on line breaking

Author: frivoal

css-ruby-1/Overview.bs

@@ -791,6 +791,7 @@ Breaking Across Lines</h3>
 
 	When there is not enough space for an entire [=ruby container=] to fit on the line,
 	the ruby may be broken wherever all levels simultaneously allow a break.
+	(See [[CSS-TEXT-3#line-breaking]] for details on line breaking.)
 	Ruby most often breaks between base-annotation sets,
 	but if the line-breaking rules allow it, can also break within a [=ruby base=]
 	(and, in parallel, its associated [=ruby annotation boxes=]).