style: add docs

 # mobile_scanner
 
+[![pub package](https://img.shields.io/pub/v/mobile_scanner.svg)](https://pub.dev/packages/mobile_scanner)
+[![mobile_scanner](https://github.com/juliansteenbakker/mobile_scanner/actions/workflows/flutter.yml/badge.svg)](https://github.com/juliansteenbakker/mobile_scanner/actions/workflows/flutter.yml)
+
 An universal scanner for Flutter based on MLKit.
 
-## Getting Started
+## Platform Support
+
+| Android | iOS | MacOS | Web | Linux | Windows |
+| :-----: | :-: | :---: | :-: | :---: | :-----: |
+|   ✔️    | ✔️  |     |   |     |      |
+
+# Usage
+
+Import `package:mobile_scanner/mobile_scanner.dart`, and use the widget with or without the controller.
+
+If you don't provide a controller, you can't control functions like the torch(flash) or switching camera.
+
+Example without controller:
+
+```dart
+import 'package:mobile_scanner/mobile_scanner.dart';
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('Mobile Scanner')),
+      body: MobileScanner(
+          onDetect: (barcode, args) {
+            final String code = barcode.rawValue;
+            debugPrint('Barcode found! $code');
+          }),
+    );
+  }
+```
+
+Example with controller and initial values:
+
+```dart
+import 'package:mobile_scanner/mobile_scanner.dart';
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('Mobile Scanner')),
+      body: MobileScanner(
+          controller: MobileScannerController(
+            facing: CameraFacing.front, torchEnabled: true),
+          onDetect: (barcode, args) {
+            final String code = barcode.rawValue;
+            debugPrint('Barcode found! $code');
+          }),
+    );
+  }
+```
+
+Example with controller and torch & camera controls:
 
-This project is a starting point for a Flutter
-[plug-in package](https://flutter.dev/developing-packages/),
-a specialized package that includes platform-specific implementation code for
-Android and/or iOS.
+```dart
+import 'package:mobile_scanner/mobile_scanner.dart';
 
-For help getting started with Flutter, view our
-[online documentation](https://flutter.dev/docs), which offers tutorials,
-samples, guidance on mobile development, and a full API reference.
+  MobileScannerController cameraController = MobileScannerController();
 
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+        appBar: AppBar(
+          title: const Text('Mobile Scanner'),
+          actions: [
+            IconButton(
+              color: Colors.white,
+              icon: ValueListenableBuilder(
+                valueListenable: cameraController.torchState,
+                builder: (context, state, child) {
+                  switch (state as TorchState) {
+                    case TorchState.off:
+                      return const Icon(Icons.flash_off, color: Colors.grey);
+                    case TorchState.on:
+                      return const Icon(Icons.flash_on, color: Colors.yellow);
+                  }
+                },
+              ),
+              iconSize: 32.0,
+              onPressed: () => cameraController.toggleTorch(),
+            ),
+            IconButton(
+              color: Colors.white,
+              icon: ValueListenableBuilder(
+                valueListenable: cameraController.cameraFacingState,
+                builder: (context, state, child) {
+                  switch (state as CameraFacing) {
+                    case CameraFacing.front:
+                      return const Icon(Icons.camera_front);
+                    case CameraFacing.back:
+                      return const Icon(Icons.camera_rear);
+                  }
+                },
+              ),
+              iconSize: 32.0,
+              onPressed: () => cameraController.switchCamera(),
+            ),
+          ],
+        ),
+        body: MobileScanner(
+            controller: cameraController,
+            onDetect: (barcode, args) {
+              final String code = barcode.rawValue;
+              debugPrint('Barcode found! $code');
+            }));
+  }
+```