[css-highlight-api] Add changes section

Author: frivoal

css-highlight-api-1/Overview.bs

@@ -544,16 +544,15 @@ Appendix B. Acknowledgements</h2>
 	Issue: Acknowledge people (other than editors) who deserve credit for this.
 </div>
 
-<!--
 <div class=non-normative>
 <h2 class="no-num" id="changes">
 Appendix C. Changes</h2>
 
 	<em>This section is non-normative</em>.
 
-	To be populated starting from FPWD
+	There have been only editorial changes since the previous <a href="https://www.w3.org/TR/2020/WD-css-highlight-api-1-20201022/">Working Draft</a>;
+	see <a href="https://services.w3.org/htmldiff?doc1=https%3A%2F%2Fwww.w3.org%2FTR%2F2020%2FWD-css-highlight-api-1-20201022%2F&doc2=https%3A%2F%2Fwww.w3.org%2FTR%2Fcss-highlight-api-1%2F">diffs</a>.
 </div>
--->
 
 	<!-- This text from the explainer seems useful, and should go somewhere. But where?
 	----