Update README.md for CameraX

@@ -12,3 +12,41 @@ dependencies {
 ```
 
 See our [release page](https://github.com/livekit/client-sdk-android/releases) for details on the current release version.
+
+## Usage
+
+### Register the CameraProvider
+
+```
+CameraXHelper.createCameraProvider(lifecycleOwner).let {
+    if (it.isSupported(application)) {
+        CameraCapturerUtils.registerCameraProvider(it)
+
+        // Save cameraProvider for unregistration later.
+        cameraProvider = it
+    }
+}
+```
+
+Your activity can act as your `LifecycleOwner` for the camera provider. If you wish to use the camera beyond the lifecycle of a single activity, consider using 
+[viewmodel-lifecycle](https://github.com/skydoves/viewmodel-lifecycle) for use within a view model (useful if your activity wants to handle rotation or other configuration changes),
+or `LifecycleService` from `androidx.lifecycle:lifecycle-service` to use in a service for backgrounded camera usage.
+
+Once registered, LiveKit will default to using CameraX when creating a camera video track.
+
+### Accessing the camera controls
+
+```
+fun zoom(factor: Float) {
+    val camera = localVideoTrack.capturer.getCameraX()?.value ?: return
+    val zoomState = camera.cameraInfo.zoomState.value ?: return
+    val currentZoom = zoomState.zoomRatio
+    val newZoom = (currentZoom * factor).coerceIn(zoomState.minZoomRatio, zoomState.maxZoomRatio)
+
+    if (newZoom != currentZoom) {
+        camera.cameraControl.setZoomRatio(newZoom)
+    }
+}
+```
+
+We provide a convenience `ScaleZoomHelper` class that can handle pinch-to-zoom functionality as well.