ACPI: ibm_acpi: Documentation the wan feature.

Document the wan feature Jeremy Fitzhardinge added to ibm_acpi.
Signed-off-by: NStefan Schmidt <stefan@datenfreihafen.org>
Acked-by: NBorislav Deianov <borislav@users.sourceforge.net>
Signed-off-by: NLen Brown <len.brown@intel.com>

Documentation/ibm-acpi.txt

@@ -33,6 +33,7 @@ detailed description):
 	- LCD brightness control
 	- Volume control
 	- Experimental: fan speed, fan enable/disable
+	- Experimental: WAN enable and disable
 
 A compatibility table by model and feature is maintained on the web
 site, http://ibm-acpi.sf.net/. I appreciate any success or failure
@@ -601,6 +602,23 @@ with the following command:
 
 	echo 'level <level>' > /proc/acpi/ibm/thermal
 
+EXPERIMENTAL: WAN -- /proc/acpi/ibm/wan
+---------------------------------------
+
+This feature is marked EXPERIMENTAL because the implementation
+directly accesses hardware registers and may not work as expected. USE
+WITH CAUTION! To use this feature, you need to supply the
+experimental=1 parameter when loading the module.
+
+This feature shows the presence and current state of a WAN (Sierra
+Wireless EV-DO) device. If WAN is installed, the following commands can
+be used:
+
+	echo enable > /proc/acpi/ibm/wan
+	echo disable > /proc/acpi/ibm/wan
+
+It was tested on a Lenovo Thinkpad X60. It should probably work on other
+Thinkpad models which come with this module installed.
 
 Multiple Commands, Module Parameters
 ------------------------------------