I an not sure if this is the best place to report possible issues in the PDF manual for the PiCamera2 library? I can move the issue or report elsewhere if not
Reading this section:

on page 89.
I think that this should either read:
(so 4096 represents a black level of 64 in 10-bit raw data)
or
(so 4096 represents a black level of 16 in 8-bit raw data)
Either that or I am very confused?