[css-text-4] Add issue.

Author: fantasai

css-text-4/Overview.bs

@@ -237,6 +237,8 @@ Text Wrap Settings: the 'text-wrap' property</h3>
 			The exact algorithm is UA-defined.
 			The algorithm should consider multiple lines when making break decisions.
 			The UA should bias for best layout over speed.
+
+			ISSUE: This feature does not have CSSWG consensus, it is being proposed in <a href="https://github.com/w3c/csswg-drafts/issues/672#issuecomment-379723243">Issue 672</a>.
 	</dl>
 
 	Regardless of the 'text-wrap' value,