[css-animations-1][css-transitions-1] Add new previous version URLs

Author: birtles

css-animations-1/Overview.bs

@@ -20,6 +20,7 @@ Level: 1
 Group: csswg
 TR: https://www.w3.org/TR/css-animations-1/
 ED: https://drafts.csswg.org/css-animations/
+Previous Version: https://www.w3.org/TR/2017/WD-css-animations-1-20171130/
 Previous Version: https://www.w3.org/TR/2013/WD-css3-animations-20130219/
 Previous Version: https://www.w3.org/TR/2012/WD-css3-animations-20120403/
 Editor: Dean Jackson, Apple Inc., dino@apple.com, w3cid 42080

css-transitions-1/Overview.bs

@@ -30,6 +30,7 @@ Shortname: css-transitions
 Group: csswg
 Level: 1
 TR: https://www.w3.org/TR/css-transitions-1/
+Previous version: https://www.w3.org/TR/2017/WD-css-transitions-1-20171130/
 Previous version: https://www.w3.org/TR/2013/WD-css3-transitions-20131119/
 ED: https://drafts.csswg.org/css-transitions/
 Editor: L. David Baron, Mozilla https://www.mozilla.org/, https://dbaron.org/, w3cid 15393