[css-contain-2] Add Previous Link

Author: frivoal

css-contain-2/Overview.bs

@@ -6,6 +6,7 @@ Status: ED
 Work Status: stable
 Group: csswg
 ED: https://drafts.csswg.org/css-contain-2/
+Previous Version: https://www.w3.org/TR/2019/WD-css-contain-2-20191015/
 TR: https://www.w3.org/TR/css-contain-2/
 Editor: Tab Atkins, Google, http://xanthir.com/contact/, w3cid 42199
 Editor: Florian Rivoal, On behalf of Bloomberg, https://florian.rivoal.net/, w3cid 43241