Corrected header file documentation comment.

include/SDL_gamecontroller.h

@@ -43,7 +43,7 @@ extern "C" {
  *  \file SDL_gamecontroller.h
  *
  *  In order to use these functions, SDL_Init() must have been called
- *  with the ::SDL_INIT_JOYSTICK flag.  This causes SDL to scan the system
+ *  with the ::SDL_INIT_GAMECONTROLLER flag.  This causes SDL to scan the system
  *  for game controllers, and load appropriate drivers.
  *
  *  If you would like to receive controller updates while the application