[css-box-4] fix IDs in changes

Author: svgeesus

css-box-4/Overview.bs

@@ -2,11 +2,13 @@
 Title: CSS Box Model Module Level 4
 Shortname: css-box
 Level: 4
-Status: ED
+Status: FPWD
 Work Status: Exploring
 Group: csswg
 ED: https://drafts.csswg.org/css-box-4/
 TR: https://www.w3.org/TR/css-box-4/
+Date: 2020-04-21
+Prepare for TR: yes
 Abstract: This specification describes the margin and padding properties, which create spacing in and around a CSS box. It may later be extended to include borders (currently described in [[css-backgrounds-3]]).
 Editor: Elika J. Etemad / fantasai, Invited Expert, http://fantasai.inkedblade.net/contact, w3cid 35400
 Ignored Terms: internal table elements, block layout
@@ -544,7 +546,7 @@ Borders {#borders}
 	Both sets of properties control the same set of borders:
 	they are just different ways of indexing each side.
 
-Changes Since CSS Level 3 {#changes}
+Changes Since CSS Level 3 {#changes-since-3}
 =========================
 
 	The following changes have been made to this module
@@ -553,7 +555,7 @@ Changes Since CSS Level 3 {#changes}
 		<li>Adding the 'margin-trim' property.
 	</ul>
 
-Changes Since CSS Level 2 {#changes}
+Changes Since CSS Level 2 {#changes-since-2}
 =========================
 
 	The following changes have been made to this module