docs: Pull LKMM documentation into dev-tools book

docs: Pull LKMM documentation into dev-tools book

Currently, LKMM docs are not included in any of kernel documentation
books.

Commit e40573a43d16 ("docs: put atomic*.txt and memory-barriers.txt
into the core-api book") covered plain-text docs under Documentation/
by using the "include::" directive along with the ":literal:" option.

As LKMM docs are not under Documentation/, the same approach would not
work due to the directive's restriction.

As a matter of fact, kernel documentation has an extended directive
by the name of "kernel-include::", which loosens such restriction and
accepts any files under the kernel source tree.

Rather than moving LKMM docs around, use the latter and pull them into
the dev-tools book next to KCSAN.

Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <7ce84a93-5cbc-420e-894a-06a0372c52ab@gmail.com>