[css-scroll-snap] update Previous

Author: svgeesus

css-scroll-snap-1/Overview.bs

@@ -6,6 +6,7 @@ TR: https://www.w3.org/TR/css-scroll-snap-1/
 Level: 1
 Status: ED
 Implementation Report: https://wpt.fyi/results/css/css-scroll-snap
+Previous Version: https://www.w3.org/TR/2021/CR-css-scroll-snap-1-20210311/
 Previous Version: https://www.w3.org/TR/2019/CR-css-scroll-snap-1-20190319/
 Previous Version: https://www.w3.org/TR/2019/CR-css-scroll-snap-1-20190131/
 Previous Version: https://www.w3.org/TR/2018/CR-css-scroll-snap-1-20180814/