Copter: prefix SingleCopter's MOT param description

This should allow single copter's MOT_ parameter descriptions to be more
easily recognised as belonging to SingleCopter when viewed on the wiki's
arducopter-parameters page

ArduCopter/Parameters.pde

@@ -1070,7 +1070,7 @@ const AP_Param::Info var_info[] PROGMEM = {
     // @Group: SS4_
     // @Path: ../libraries/RC_Channel/RC_Channel.cpp
     GGROUP(single_servo_4,    "SS4_", RC_Channel),
-    // @Group: H_
+    // @Group: (SingleCopter)MOT_
     // @Path: ../libraries/AP_Motors/AP_MotorsSingle.cpp
     GOBJECT(motors, "MOT_",           AP_MotorsSingle),