Update locusID documentation to capture privacy around LocusId usage.

Bug: 194374710
Test: n/a

Change-Id: I7e72e1394562788c31e2a6c86f43a028a3e85e0b
diff --git a/core/java/android/content/LocusId.java b/core/java/android/content/LocusId.java
index a04fbd1..b6cdd96 100644
--- a/core/java/android/content/LocusId.java
+++ b/core/java/android/content/LocusId.java
@@ -62,6 +62,9 @@
  *   <li>Configuring your app to launch the chat conversation through the
  *   {@link Intent#ACTION_VIEW_LOCUS} intent.
  * </ul>
+ *
+ * NOTE: The LocusId is only used by an on-device intelligence service provided by the Android
+ * System, see {@link ContentCaptureManager} for more details.
  */
 public final class LocusId implements Parcelable {