[css-multicol] Add change section

Author: frivoal

css-multicol/Overview.bs

@@ -1713,6 +1713,19 @@ Pagination and overflow outside multicol elements</h3>
 		Due to column balancing, the last paragraph is split across three columns.
 	</div>
 
+<h2 class="no-num" id="changes">Appendix B. Changes</h2>
+
+This appendix is <em>informative</em>.
+
+This appendix describes changes from the
+<a href="https://www.w3.org/TR/2011/CR-css3-multicol-20110412/"
+   >Candidate Recommendation (CR) of 12 April 2011</a>.
+
+<ul>
+	<li>TBD
+	<li>Clarify that column-span causes the element to become a formatting context even if it is not in a multicol
+</ul>
+
 <h2 class=no-num id=acknowledgments>
 Acknowledgments</h2>