Update known-issues-native.md

deleted PiP clause and added CallKit clause

Author: lisaleehan

articles/communication-services/concepts/voice-video-calling/known-issues-native.md

@@ -18,9 +18,9 @@ This article provides known issues related to using the Azure Communication Serv
 
 When utilizing Android API emulators on Android 5.0 (API level 21) and Android 5.1 (API level 22), some crashes are expected.
 
-## iOS ongoing video Picture in Picture (PiP)
+## iPhone and iPad simulators not working if CallKit is enabled
 
-Incoming video stops when app goes to background. If the application is in foreground the video renders correctly.
+CallKit only works if an application is deployed to real devices. In simulators, using CallKit will cause it to crash. Developers on simulators are encouraged to turn off CallKit in local development.
 
 ## Native SDK UI Library known issues