doc(minor): document alternative usb plug event source for kobo

frontend/device/kobo/device.lua

@@ -130,6 +130,7 @@ function Kobo:init()
                     return "Light"
                 end
             end,
+            -- NOTE: usb hotplug event is also available in /tmp/nickel-hardware-status
             [102] = "Home",
             [116] = "Power",
         }

platform/kobo/enable-wifi.sh

@@ -9,4 +9,6 @@ sleep 1
 ifconfig eth0 up
 wlarm_le -i eth0 up
 
-pidof wpa_supplicant >/dev/null || env -u LD_LIBRARY_PATH wpa_supplicant -s -ieth0 -O /var/run/wpa_supplicant -c/etc/wpa_supplicant/wpa_supplicant.conf -B
+pidof wpa_supplicant >/dev/null || \
+    env -u LD_LIBRARY_PATH \
+    wpa_supplicant -s -ieth0 -O /var/run/wpa_supplicant -c/etc/wpa_supplicant/wpa_supplicant.conf -B