[PATCH] Kdump documentation update

Update the kdump documentation to reflect the changes due to recent kernel
config option changes for kexec and kdump.

Signed-off-by: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>