Sync SDL3 wiki -> header

[ci skip]

include/SDL3/SDL_stdinc.h

@@ -2556,7 +2556,7 @@ extern SDL_DECLSPEC Uint32 SDLCALL SDL_StepUTF8(const char **pstr, size_t *pslen
  *
  * \threadsafety It is safe to call this function from any thread.
  *
- * \since This function is available since SDL 3.1.5.
+ * \since This function is available since SDL 3.0.0.
  */
 extern SDL_DECLSPEC Uint32 SDLCALL SDL_StepBackUTF8(const char *start, const char **pstr);
 

include/SDL3/SDL_timer.h

@@ -133,7 +133,7 @@ extern SDL_DECLSPEC void SDLCALL SDL_DelayNS(Uint64 ns);
  *
  * \param ns the number of nanoseconds to delay.
  *
- * \since This function is available since SDL 3.1.5.
+ * \since This function is available since SDL 3.0.0.
  */
 extern SDL_DECLSPEC void SDLCALL SDL_DelayPrecise(Uint64 ns);