Update isRestrictedProfile javadoc for QUERY_USERS

isRestrictedProfile only began allowing QUERY_USERS starting in Android
V; prior to that, it didn't. So this is mentioned in the javadoc.

Bug: 274673121
Test: N/A. It's just documentation.
Change-Id: Ic68594d6987cc8796477394f2e2df3411c78a1dd