Formatted kernel documentation at kernel.org

For the last couple of release cycles, the kernel's ongoing transition tothe Sphinx documentation system has left kernel.org behind. Thanks to somework by Konstantin Ryabitsev, that situation has now been remedied, andkernel.org has the formatteddocumentation generated from the current -rc kernel. The DocBook-generated documentsremain available for as long as DocBook stays in use. (For thoseinterested in the linux-next version of the documentation, the version on LWN's server isusually up to date; it currently has the changes that are queued for 4.10.)