[css3-page] Update Changes

Author: SimonSapin

css3-page/Overview.html

@@ -3460,6 +3460,11 @@ <h2 class=no-num id=changes>Changes</h2>
       Content module. <a href="#CSS3-IMAGES"
       rel=biblioentry>[CSS3-IMAGES]<!--{{CSS3-IMAGES}}--></a>
 
+     <li>The default stacking order of page-magin boxes is now defined.
+
+     <li>Support for the ‘<code class=property>z-index</code>’ property
+      on page-margin boxes is not optional anymore.
+
      <li>Many miscellaneous clarifications and editorial improvements have
       been incorporated.
     </ul>

css3-page/Overview.src.html

@@ -2517,6 +2517,11 @@ <h2 class="no-num" id="changes">Changes</h2>
     and moved to the CSS3 Image Values and Replaced Content module.
     [[CSS3-IMAGES]]
 
+  <li>The default stacking order of page-magin boxes is now defined.
+
+  <li>Support for the 'z-index' property on page-margin boxes
+    is not optional anymore.
+
   <li>Many miscellaneous clarifications
     and editorial improvements have been incorporated.