Copter: add A-Tail to FRAME parameter description

ArduCopter/Parameters.pde

@@ -381,7 +381,7 @@ const AP_Param::Info var_info[] PROGMEM = {
     // @Param: FRAME
     // @DisplayName: Frame Orientation (+, X or V)
     // @Description: Controls motor mixing for multicopters.  Not used for Tri or Traditional Helicopters.
-    // @Values: 0:Plus, 1:X, 2:V, 3:H, 4:V-Tail, 10:Y6B (New)
+    // @Values: 0:Plus, 1:X, 2:V, 3:H, 4:V-Tail, 5:A-Tail, 10:Y6B (New)
     // @User: Standard
     GSCALAR(frame_orientation, "FRAME",             AP_MOTORS_X_FRAME),