docs: ABI: sysfs-bus-nvdimm: use the right format for ABI

This ABI is not following the format described at ABI/README.

Use it, filling in the blanks with the git log that added it,
and using the current e-mail from Dan.
Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/9ec379cbf6dcf65ce3039c3671baf7bcaea532f4.1604042072.git.mchehab+huawei@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/ABI/testing/sysfs-bus-nvdimm

+What:          nvdimm
+Date:          July 2020
+KernelVersion: 5.8
+Contact:       Dan Williams <dan.j.williams@intel.com>
+Description:
+
 The libnvdimm sub-system implements a common sysfs interface for
 platform nvdimm resources. See Documentation/driver-api/nvdimm/.