Add documentation on usage of net-utils-connectivity-apks am: 514f40b0c3

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/3220095

Change-Id: Ia8fc9443cb84337cf6977c3fad60d499bf99bde7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>