docs: ABI: vdso: 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 Andy.

Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/28c7cf3a71e15fb7499b70ec8f38c2efaaf4add2.1604042072.git.mchehab+huawei@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>