acer-wmi - Add documentation

Add some initial documentation detailing what acer-wmi is, and how to use
it. Update the Kconfig entry with a reference to the documentation.

Signed-off-by: Carlos Corbacho <carlos@strangeworlds.co.uk>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 830f51c..92a85ee 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -114,6 +114,9 @@
 	  wireless radio and bluetooth control, and on some laptops,
 	  exposes the mail LED and LCD backlight.
 
+	  For more information about this driver see
+	  <file:Documentation/laptops/acer-wmi.txt>
+
 	  If you have an ACPI-WMI compatible Acer/ Wistron laptop, say Y or M
 	  here.