[css-cascade] update issue text

Author: fantasai

css-cascade/Overview.bs

@@ -64,7 +64,8 @@ Importing Style Sheets: the ''@import'' rule</h2>
 	(collectively, the <dfn>import conditions</dfn>)
 	state the conditions under which it applies.
 
-	Issue: Syntax for incorporating <<supports-condition>> is currently under discussion; suggestions and feedback welcome!
+	Issue: Feedback on the <<supports-condition>> syntax is hereby solicited,
+	since none so far has been received.
 
 	If a <<string>> is provided,
 	it must be interpreted as a <<url>> with the same value.