docs: ntb.txt: use Sphinx notation for the two ascii figures

In order to make it to build with Sphinx, we need to fix the
notation for two ascii artwork.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Mauro Carvalho Chehab 2019-04-10 06:56:23 -03:00 • committed by Jonathan Corbet
commit 3ac10b0255