doc: fix table formatting in markdown

I ran a simple table formatter
from https://gist.github.com/glimchb/58416b643df31b27332062d775017d85


using tabulate python package

this will help with git diff on next patch when
I auto generate the entire markdown file

Change-Id: If7897b34a13b441392e68aa25cab2679517424ed
Signed-off-by: Boris Glimcher <Boris.Glimcher@emc.com>
Reviewed-on: https://review.spdk.io/c/spdk/spdk/+/26087


Reviewed-by: Jim Harris <jim.harris@nvidia.com>
Reviewed-by: Konrad Sztyber <ksztyber@nvidia.com>
Reviewed-by: Tomasz Zawadzki <tomasz@tzawadzki.com>
Tested-by: SPDK Automated Test System <spdkbot@gmail.com>