doc: note about non-existent files in watchFile
Refer: https://github.com/nodejs/io.js/pull/2093#discussion_r34343965
cc @brendanashworth @bnoordhuis
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Refer: https://github.com/nodejs/io.js/pull/2093#discussion_r34343965
cc @brendanashworth @bnoordhuis