[css-display-3] Update Changes list

Author: fantasai

css-display-3/Overview.bs

@@ -1389,12 +1389,14 @@ Changes</h2>
 
 	<ul>
 		<li id="change-parent">
-			Defined <a>parent box</a>.
+			Defined box tree parentage; see <a>parent box</a>.
 		<li id="change-abspos">
 			Added definition of <a>absolutely positioned</a> to the glossary;
 			<a href="https://www.w3.org/TR/CSS2/visuren.html#absolutely-positioned">copied from CSS2</a> for easier referencing.
 		<li id="change-bidi-fragment">
 			Added cross-references to various forms of fragmentation in [[#intro]].
+		<li id="change-table-grid-box">
+			Renamed “table box” to “table grid box” to more easily distinguish from “table wrapper box”.
 	</ul>
 
 <h3 id="changes-wd">