kB (*kilo* byte) unit means 1000 bytes, whereas KiB ("kibibyte")
means 1024 bytes. KB was misused: replace kB or KB with KiB when
appropriate.
Same change for MB and GB which become MiB and GiB.
Change the output of Tools/iobench/iobench.py.
Round also the size of the documentation from 5.5 MB to 5 MiB.
Clean up `Misc/README.AIX` for addressed known issues.
- Issues that have been marked fixed: #11184, #11185
- Issues resolved by new AIX version: #1745108
- Issues resolved, but not yet marked fixed/closed: #11188
Signed-off-by: Eric N. Vander Weele <ericvw@gmail.com>