Align repo-type with documented taxonomy (w3c#18)

s/note-track/note/ per https://w3c.github.io/w3c.json.html

Author: dontcallmedom

w3c.json

@@ -1,5 +1,5 @@
  {
     "group":      [49309]
 ,   "contacts":   ["wseltzer","weiler"]
-,   "repo-type":  "note-track"
+,   "repo-type":  "note"
 }