Added peerlist docs

docs/flutter/v2/how-to-guides/set-up-video-conferencing/preview.mdx

@@ -86,6 +86,13 @@ class Preview implements HMSPreviewListener{
       List<HMSAudioDevice>? availableAudioDevice}) {
          /// Get notified when the audio device is changed: https://www.100ms.live/docs/flutter/v2/features/audio-output-routing#adding-audio-device-change-event-listener-android-only
    }
+
+   @override
+   void onPeerListUpdate(
+      {required List<HMSPeer> addedPeers, required List<HMSPeer> removedPeers}){
+         ///When a room is joined we can get the list of peers in the room from `addedPeers`
+         /// Get notified when a peer is added or removed: https://www.100ms.live/docs/flutter/v2/features/update-listener-enums#hms-peer-update
+      }
 }
 ```
 
@@ -265,5 +272,14 @@ abstract class HMSPreviewListener {
    void onAudioDeviceChanged(
       {HMSAudioDevice? currentAudioDevice,
       List<HMSAudioDevice>? availableAudioDevice});
+
+   ///Upon joining a room with existing peers, onPeerListUpdated will be called with the list of peers present
+   ///in the room instead of getting onPeerUpdate for each peer in the room.
+   ///Subsequent peer joins/leaves would be notified via both onPeerUpdate and onPeerListUpdated
+   /// - Parameters:
+   ///  - addedPeers: List of peers who joined the room
+   ///  - removedPeers: List of peers who left the room
+   void onPeerListUpdate(
+      {required List<HMSPeer> addedPeers, required List<HMSPeer> removedPeers});
 }
 ```