Add icon for AC mode

Author: fvincenzo

scripts/battery.sh

@@ -167,7 +167,7 @@ main()
   if [ -z "$bat_stat" ]; then # Test if status is empty or not
     echo "$bat_label $bat_perc"
   elif [ -z "$bat_perc" ]; then # In case it is a desktop with no battery percent, only AC power
-    echo ""
+    echo " AC"
   else
     echo "$bat_label$bat_stat $bat_perc"
   fi