docs: ABI: change read/write attributes

docs: ABI: change read/write attributes

Unfortunately, (R) and (W) are valid markups for enumerated
lists, as described at:
	https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#enumerated-lists

So, we ned to replace them by:

	(R) -> (Read)
	(W) -> (Write)

As otherwise, (R) will be displayed as R., with is not what
it is desired.

There's no need to touch (RO) and (RW).

Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/6e81ad8064f3ed4f8dc265086fdf1c618043f935.1604042072.git.mchehab+huawei@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>