[PATCH] Kdump documentation update: kexec-tools update

Mohan Kumar suggested making kexec-tools-testing.tar.gz a link to the
latest version.  I have done this and this patch updates the documentation
accordingly.

Signed-off-by: Simon Horman <horms@verge.net.au>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>