Documentation: dev-tools: Add a section for static analysis tools

Complement the Kernel Testing Guide documentation page by adding a
section about static analysis tools.

Signed-off-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
Acked-by: Daniel Latypov <dlatypov@google.com>
Acked-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Julia Lawall <julia.lawall@inria.fr>
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>