[css-inline-3] Tweak leading-trim warning.

Author: fantasai

css-inline-3/Overview.bs

@@ -715,10 +715,10 @@ Leading Control: the 'leading-trim-over' and 'leading-trim-under' properties and
 	and is likely to change significantly
 	as design critiques and use cases are registered.
 	Values and property names may be added, dropped, and/or renamed,
-	and the overall syntax or behavior may change.
-	Do not implement (yet).
-	The CSSWG particularly invites feedback on
-	which font metrics need corresponding keyword values.
+	and the overall syntax or behavior may change,
+	particularly in response to authoring and robustness considerations
+	for handling descendant boxes.
+	<strong>Do not implement (yet).</strong>
 
 	To ensure consistent spacing in the basic case of running text,
 	CSS line layout introduces leading both above and below