Mark repo as host of rec-track work

Per https://w3c.github.io/w3c.json.html

Author: dontcallmedom

w3c.json

@@ -2,4 +2,5 @@
     "group":      ["49799"]
 ,   "contacts":   ["sideshowbarker"]
 ,   "shortName":  "webdriver"
+,   "repo-type":  "rec-track"
 }