chore: Mark repo as host of software development (#154)

It looks like the repo is now more about the polyfill than spec development, so I'm suggesting to use repo-type: tool instead of cg-report

w3c.json

@@ -1,5 +1,5 @@
  {
     "group":      [80485]
 ,   "contacts":   ["marcoscaceres"]
-,   "repo-type":  "cg-report"
+,   "repo-type":  "tool"
 }