chore: improve the help of preview command

Author: Fatme

docs/man_pages/project/testing/preview.md

@@ -7,9 +7,15 @@ position: 1
 
 Usage | Synopsis
 ---|---
-Produces a QR code for deployment in the Preview app. | `tns preview`
+Produces a QR code which can be used to priview the app on a device without the need to install various SDKs and tools or configure your environment for local iOS or Android development. | `tns preview`
 
-Enjoy NativeScript without any local setup. All you need is a couple of companion apps installed on your devices. When you save changes to the project, the changes are automatically synchronized to Preview app on your device.
+To scan the QR code and deploy your app on a device, you need to have the NativeScript Playground app:
+    App Store (iOS): https://itunes.apple.com/us/app/nativescript-playground/id1263543946?mt=8&ls=1
+    Google Play (Android): https://play.google.com/store/apps/details?id=org.nativescript.play
+
+After scanning the QR code with the scanner provided in the NativeScript Playground app, your app will be launched on your device through the Preview app. Additionally, any changes made to your project will be automatically synchronized with the deployed app.
+
+Limitation: The Preview app comes with a predefined set of NativeScript plugins. If your app utilizes a plugin that is not present in the Preview app, you will see a warning message and your app might not work as expected.
 
 ### Options
 `--bundle` - Specifies that a bundler (e.g. webpack) should be used if one is present. If no value is passed will default to `webpack`