[K/N] Update ObjectTransfer.kt documentation for the new MM

kotlin-native/runtime/src/main/kotlin/kotlin/native/concurrent/ObjectTransfer.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * Copyright 2010-2022 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
  * that can be found in the LICENSE file.
  */
 
@@ -9,6 +9,9 @@ import kotlinx.cinterop.*
 import kotlin.native.internal.Frozen
 
 /**
+ * Note: modern Kotlin/Native memory manager allows to share objects between threads without additional ceremonies,
+ * so TransferMode has effect only in legacy memory manager.
+ *
  *  ## Object Transfer Basics.
  *
  *  Objects can be passed between threads in one of two possible modes.