add a note to fix some weird behaviour in storage/file

storage/file.js

@@ -343,7 +343,7 @@ const messageBin = (env, chanName, msgBin, cb) => {
             chan.onError.splice(chan.onError.indexOf(complete), 1);
             if (!cb) { return; }
             //chan.messages.push(msg);
-            chan.atime = +new Date();
+            chan.atime = +new Date(); // FIXME seems like odd behaviour that not passing a callback would result in not updating atime...
             complete();
         });
     });