Merge "Improve docs for the tzdata file" am: acf7059a96 am: e9687e9690 am: f01337eb91 am: 2002dee6d0

Original change: https://android-review.googlesource.com/c/platform/system/timezone/+/1478316

Change-Id: I31fdc1282b8f076e8a6e41e66551d2c109405f69