doc: fix example JSON in markdown

I ran a simple json linter and fixed all issues.
Linter can be found here:
https://gist.github.com/glimchb/8b1b00e371a43a40e7dd7339ec0e9643



by design I don't want to commit linter to spdk repo yet.
since i'm working on code generation that will make it obsolete.

I also aligned functions to the same pattern as preparation for
the code generation that will come next.

Change-Id: I1c8b2bd75224677a665f3a5dd81249e4efd12def
Signed-off-by: Boris Glimcher <Boris.Glimcher@emc.com>
Reviewed-on: https://review.spdk.io/c/spdk/spdk/+/26072


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