[css-transforms-1] Add an entry to Changes section

Simplified grammar of transform functions. (No normative impact.)

Author: lahmatiy

css-transforms-1/Overview.bs

@@ -1529,6 +1529,7 @@ At this point there are no information about potential privacy or security conce
 <h3 class="no-num" id="CR20190214">Since the <a href="https://www.w3.org/TR/2019/CR-css-transforms-1-20190214/">14 February 2019 Candidate Recommendation</a></h3>
 
 * Relax syntax of <a element-attr for>transform</a> attribute: Do not require commas between <<transform-list>> items.
+* Simplified grammar of transform functions. (No normative impact.)
 * Editorial changes.
 
 <h3 class="no-num" id="WD20181130">Since the <a href="https://www.w3.org/TR/2018/WD-css-transforms-1-20181130/">30 November 2018 Working Draft</a></h3>