Better Doxygen for topics, no code changes

src/drivers/drv_rc_input.h

@@ -67,6 +67,11 @@
  */
 #define RC_INPUT_RSSI_MAX	255
 
+/**
+ * @addtogroup topics
+ * @{
+ */
+
 /**
  * Input signal type, value is a control position from zero to 100
  * percent.
@@ -141,6 +146,10 @@ struct rc_input_values {
 	rc_input_t		values[RC_INPUT_MAX_CHANNELS];
 };
 
+/**
+ * @}
+ */
+
 /*
  * ObjDev tag for R/C inputs.
  */