pen: Fixed incorrect comment.

src/events/SDL_pen_c.h

@@ -81,7 +81,7 @@ extern void SDL_SendPenAxis(Uint64 timestamp, SDL_PenID instance_id, SDL_Window
 // Backend calls this when a pen's button changes, to generate events and update state.
 extern void SDL_SendPenButton(Uint64 timestamp, SDL_PenID instance_id, SDL_Window *window, Uint8 button, bool down);
 
-// Backend calls this when a pen's button changes, to generate events and update state.
+// Backend calls this when a pen's proximity changes, to generate events and update state.
 extern void SDL_SendPenProximity(Uint64 timestamp, SDL_PenID instance_id, SDL_Window *window, bool in);
 
 // Backend can optionally use this to find the SDL_PenID for the `handle` that was passed to SDL_AddPenDevice.