[css-line-grid-1] Update Change Log

Author: xfq

css-line-grid-1/Overview.bs

@@ -757,6 +757,8 @@ Since <a href="https://www.w3.org/TR/2014/WD-css-line-grid-1-20140916/">Septembe
 		<li>Added flex and grid container applicability for line-grid</li>
 		<li>Added normative text for line-snap examples</li>
 		<li>Added @page and root element line grid handling</li>
+		<li>Made the dependency on line-height-step explicit</li>
+		<li>''match-parent'' creates new line grid for orthoganal flows</li>
 	</ul>
 
 <h3 class="no-num" id="20140403">