More documentation about TETHERING_VIRTUAL

Bug: 353392669
Test: N/A
Change-Id: Idaff2c67eccfa3000964c185feba9eaf61260c05
diff --git a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
index ae0161d..0f5a014 100644
--- a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
+++ b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
@@ -198,6 +198,10 @@
 
     /**
      * VIRTUAL tethering type.
+     *
+     * This tethering type is for providing external network to virtual machines
+     * running on top of Android devices, which are created and managed by
+     * AVF(Android Virtualization Framework).
      * @hide
      */
     @FlaggedApi(Flags.TETHERING_REQUEST_VIRTUAL)