Merge "AttestationKey documentation" am: c46f9da49f am: 5df02652c1 am: 237ecec162 am: ff9fce151e am: 9125680878 am: b9e97afe4d

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/1674665

Change-Id: I3e0e4f5b98274427fefec3660c2b78383e257b81