Update previous version URI.

Author: gkellogg

index.html

@@ -24,8 +24,8 @@
 
       // if there is a previously published draft, uncomment this and set its YYYY-MM-DD date
       // and its maturity status
-      prevVersion:            "https://www.w3.org/TR/2018/WD-json-ld11-20181011/",
-      previousPublishDate:    "2018-10-11",
+      prevVersion:            "https://www.w3.org/TR/2018/WD-json-ld11-20181214/",
+      previousPublishDate:    "2018-12-14",
       previousMaturity:       "WD",
       prevRecURI:             "https://www.w3.org/TR/2014/REC-json-ld-20140116/",
       github:                 "https://github.com/w3c/json-ld-syntax/",