Documentation: add Linux Kernel Development book

The Linux Kernel Development book by Robert Love has been recommended to me
by multiple kernel hackers. Worth having in the list of books in
kernel-docs.txt for newbies looking for good learning resources.

Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>