Documentation - Create laptops sub-directory

There are currently various laptop drivers floating about with no central
place for their documentation, which is currently scattered around the top
level Documentation/ directory.

So, as a first step, lets create a Documentation sub-directory, and update
the relevant index files. The work of then moving the existing laptop
driver related documentation will then be handled later.

Signed-off-by: Carlos Corbacho <carlos@strangeworlds.co.uk>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
CC: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
CC: Mattia Dongili <malattia@linux.it>
Signed-off-by: Len Brown <len.brown@intel.com>