Merge "Update Documentation for EPOCH_TIME." into sc-qpr1-dev am: 922f2b0bca am: 828a063f3c

Original change: https://googleplex-android-review.googlesource.com/c/platform/hardware/interfaces/+/15618006

Change-Id: I2e99fe079b9257f54e7304fa41e92a8d6653db2a