fix(Unity): ANR mechanism (#15505)

Author: bitsandfoxes

docs/platforms/unity/configuration/app-not-responding/index.mdx

@@ -35,6 +35,14 @@ Since the ANR integration creates an exception on a background thread, based on
 
 Since the Unity SDKs [line number support](/platforms/unity/configuration/il2cpp) is limited to actually thrown exceptions, the integration does not provide you with line numbers in the captured ANR issues.
 
+### Automatic Disabling of Native ANR Detection
+
+To prevent duplicate ANR events, the Unity SDK automatically disables native ANR detection when initializing on Android and iOS platforms. This happens regardless of your Unity ANR setting. The Unity SDK's ANR detection is designed to work within the Unity runtime environment, where native detection mechanisms may not function correctly or would report duplicate events.
+
+### ANR Mechanism for Event Filtering
+
+Unity ANR events are reported with `MainThreadWatchdog` as the mechanism. You can use this to filter or categorize events in Sentry.
+
 ## Configuration
 
 ANR detection is enabled by default in Sentry, but you can opt-out through the editor window by going to `Tools -> Sentry -> Advanced -> ANR Detection`. You can also set the ANR timeout there.