Merge "Adding additional docs for OemNetworkPreferences" am: 1258b5fec3 am: a9daf47946

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1606593

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I0a4cff353357a270f126a74d2648de755c64a6ee