Move out-of-date stuff to readme.io so we don't have to maintain it in two places

package.json

@@ -49,7 +49,7 @@
     },
     "licenses": [],
     "c9plugins": {
-        "c9.ide.language": "#de3c644b88",
+        "c9.ide.language": "#afda452919",
         "c9.ide.language.css": "#afda1f867c",
         "c9.ide.language.generic": "#87a4a44671",
         "c9.ide.language.html": "#fa4833e117",