You don’t need to configure anything for file watching; you enable it with the --watch CLI option. However, if you want to be gentle with your file watching limit and your notebook charge, you might want to restrict file watching to specific folders. Per default, it watches the entire folder that contains the config file. The configuration expects an array of strings. The strings are paths relative to your configuration file. It might look like this:

module.exports = {
    // configuration of your pipelines...

    watchDirs: ["./src", "./lib"]
}