Plane: Update THR_FAILSAFE param metadata

ArduPlane/Parameters.cpp

@@ -460,7 +460,7 @@ const AP_Param::Info Plane::var_info[] = {
 
     // @Param: THR_FAILSAFE
     // @DisplayName: Throttle and RC Failsafe Enable
-    // @Description: This enables failsafe on loss of RC input. How this is detected depends on the type of RC receiver being used. For older radios an input below the THR_FS_VALUE is used to trigger failsafe. For newer radios the failsafe trigger is part of the protocol between the autopilot and receiver. A value of 2 means that the RC input won't be used when throttle goes below the THR_FS_VALUE, but it won't trigger a failsafe
+    // @Description: 0 disables the failsafe. 1 enables failsafe on loss of RC input. This is detected either by throttle values below THR_FS_VALUE, loss of receiver valid pulses/data, or by the FS bit in receivers that provide it, like SBUS. A programmable failsafe action will occur and RC inputs, if present, will be ignored. A value of 2 means that the RC inputs won't be used when RC failsafe is detected by any of the above methods, but it won't trigger an RC failsafe action.
     // @Values: 0:Disabled,1:Enabled,2:EnabledNoFailsafe
     // @User: Standard
     GSCALAR(throttle_fs_enabled,    "THR_FAILSAFE",   int(ThrFailsafe::Enabled)),