uwb: doc: add documentation for ASIE sysfs attribute

Document the /sys/class/uwb_rc/uwbN/ASIE sysfs attribute
Signed-off-by: NThomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/ABI/testing/sysfs-class-uwb_rc

@@ -43,6 +43,19 @@ Description:
                 Reading returns the currently active channel, or -1 if
                 the radio controller is not beaconing.
 
+What:           /sys/class/uwb_rc/uwbN/ASIE
+Date:           August 2014
+KernelVersion:  3.18
+Contact:        linux-usb@vger.kernel.org
+Description:
+
+                The application-specific information element (ASIE)
+                included in this device's beacon, in space separated
+                hex octets.
+
+                Reading returns the current ASIE.  Writing replaces
+                the current ASIE with the one written.
+
 What:           /sys/class/uwb_rc/uwbN/scan
 Date:           July 2008
 KernelVersion:  2.6.27