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

kotlin-native/runtime/src/main/kotlin/kotlin/Throwable.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2020 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.
  */
 
@@ -171,7 +171,7 @@ public actual inline fun Throwable.printStackTrace(): Unit = printStackTrace()
  * Adds the specified exception to the list of exceptions that were
  * suppressed in order to deliver this exception.
  *
- * Does nothing if this [Throwable] is frozen.
+ * Legacy MM: does nothing if this [Throwable] is frozen.
  */
 @SinceKotlin("1.4")
 @OptIn(FreezingIsDeprecated::class)