This fix tries to fix the discrepancy between `docker stats` and
`docker run` where `docker run` uses RAMInBytes for all memory
related inputs but `docker stats` uses HumanSize for all memory
related outputs.
To be consistent, `docker stats` needs to use BytesSize for all
memory related outputs to conform to RAMInBytes in `docker run`.
This fix addresses this issue. As BytesSize is used, the test
cases needs to be adjusted to match `KiB/MiB/GiB` instead of
`KB/MB/GB`.
The documentation has also been updated.
This fix fixes#21765.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>