[css-2018] Use WG-NOTE instead of NOTE

Author: xfq

css-2018/Overview.bs

@@ -2,7 +2,7 @@
 Title: CSS Snapshot 2018
 Shortname: css-2018
 Level: 0
-Status: NOTE
+Status: WG-NOTE
 Group: CSSWG
 Work Status: revising
 URL: https://drafts.csswg.org/css-2018/