[css-box-3] Update metadata from publication.

Author: fantasai

css-box-3/Overview.bs

@@ -3,11 +3,11 @@ Title: CSS Box Model Module Level 3
 Shortname: css-box
 Level: 3
 Status: ED
-Work Status: Exploring
+Work Status: Refining
 Group: csswg
 ED: https://drafts.csswg.org/css-box-3/
 TR: https://www.w3.org/TR/css-box-3/
-Previous Version: https://www.w3.org/TR/2018/WD-css-box-3-20180802/
+Previous Version: https://www.w3.org/TR/2018/WD-css-box-3-20181218/
 Abstract: This specification describes the margin and padding properties, which create spacing in and around a CSS box.
 Editor: Elika J. Etemad / fantasai, Invited Expert, http://fantasai.inkedblade.net/contact, w3cid 35400
 Ignored Terms: internal table elements, block layout