Add some more public doc for MacAddress

Bug: 140807677
Test: doc-only change
Original-Change: https://android-review.googlesource.com/1354447
Merged-In: I0f6e59eda42fd92ec34db0e9bc2d26d2e83d41d0
Change-Id: I0f6e59eda42fd92ec34db0e9bc2d26d2e83d41d0
1 file changed
tree: 2ea86038a40a54279747fe61c450dd5302783a27
  1. core/
  2. services/
  3. tests/