improve examples readme

Author: fadi-george

examples/demo/README.md

@@ -1,16 +1,41 @@
-# demo
+# OneSignal Flutter SDK Demo
 
-A new Flutter project.
+A demo app showcasing all OneSignal Flutter SDK features including push notifications, in-app messaging, user management, tags, triggers, outcomes, and more.
 
-## Getting Started
+## Prerequisites
 
-This project is a starting point for a Flutter application.
+- Flutter 3.7+
+- Android emulator or iOS simulator (or a physical device)
+- For iOS: Xcode with a valid signing configuration
 
-A few resources to get you started if this is your first Flutter project:
+## Setup
 
-- [Lab: Write your first Flutter app](https://docs.flutter.dev/get-started/codelab)
-- [Cookbook: Useful Flutter samples](https://docs.flutter.dev/cookbook)
+```bash
+flutter pub get
+```
 
-For help getting started with Flutter development, view the
-[online documentation](https://docs.flutter.dev/), which offers tutorials,
-samples, guidance on mobile development, and a full API reference.
+For iOS, install CocoaPods dependencies:
+
+```bash
+cd ios && pod install && cd ..
+```
+
+## Run
+
+```bash
+flutter run
+```
+
+If multiple devices are connected, select one when prompted or specify it:
+
+```bash
+flutter run -d <device_id>
+```
+
+## Configuration
+
+The app uses a default OneSignal App ID for testing. To use your own, update the `oneSignalAppId` constant in `lib/main.dart`.
+
+## Build Guide
+
+See [../build.md](../build.md) for the full set of prompts and requirements used to build this app.