Append / to ED link

https://drafts.csswg.org/selectors redirects.

Author: foolip

selectors-4/Overview.bs

@@ -5,7 +5,7 @@ Shortname: selectors
 Level: 4
 Status: ED
 Work Status: Refining
-ED: https://drafts.csswg.org/selectors
+ED: https://drafts.csswg.org/selectors/
 TR: https://www.w3.org/TR/selectors-4/
 Previous Version: https://www.w3.org/TR/2018/WD-selectors-4-20180201/
 Previous Version: https://www.w3.org/TR/2013/WD-selectors4-20130502/