added comment about when geonames warning can go away

sanitizer/search.js

@@ -16,6 +16,7 @@ var sanitizeAll = require('../sanitizer/sanitizeAll'),
       geo_search: require('../sanitizer/_geo_search'),
       boundary_country: require('../sanitizer/_boundary_country'),
       categories: require('../sanitizer/_categories'),
+      // this can go away once geonames has been abrogated
       geonames_warnings: require('../sanitizer/_geonames_warnings')
     };