sony-laptop - Move sony-laptop.txt to Documentation/laptops

Also update references to sony-laptop.txt in Kconfig.

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

Documentation/laptops/00-INDEX

@@ -1,4 +1,6 @@
 00-INDEX
 	- This file
+sony-laptop.txt
+	- Sony Notebook Control Driver (SNC) Readme.
 thinkpad-acpi.txt
 	- information on the (IBM and Lenovo) ThinkPad ACPI Extras driver.