include: Fixed up some minor documentation gaps.

include/SDL3/SDL_sensor.h

@@ -23,6 +23,10 @@
  * # CategorySensor
  *
  * SDL sensor management.
+ *
+ * In order to use these functions, SDL_Init() must have been called
+ * with the SDL_INIT_SENSOR flag.  This causes SDL to scan the system
+ * for sensors, and load appropriate drivers.
  */
 
 #ifndef SDL_sensor_h_
@@ -40,15 +44,6 @@ extern "C" {
 /* *INDENT-ON* */
 #endif
 
-/**
- *  SDL_sensor.h
- *
- *  In order to use these functions, SDL_Init() must have been called
- *  with the SDL_INIT_SENSOR flag.  This causes SDL to scan the system
- *  for sensors, and load appropriate drivers.
- */
-
-struct SDL_Sensor;
 typedef struct SDL_Sensor SDL_Sensor;
 
 /**