update note about npm start [skip ci]

Author: mojavelinux

README.adoc

@@ -161,6 +161,8 @@ To build the UI and preview it in a local web server, run the `preview` command:
 Alternatively, you can use the following command:
 
  $ npm start
+
+In fact, if you use `npm start`, you don't need to have the Gulp CLI installed.
 ====
 
 You'll see a URL listed in the output of this command: