Sync SDL3 wiki -> header

[ci skip]

include/SDL3/SDL_properties.h

@@ -119,7 +119,9 @@ extern SDL_DECLSPEC SDL_PropertiesID SDLCALL SDL_CreateProperties(void);
  * \returns true on success or false on failure; call SDL_GetError() for more
  *          information.
  *
- * \threadsafety It is safe to call this function from any thread.
+ * \threadsafety It is safe to call this function from any thread. This
+ *               function acquires simultaneous mutex locks on both the source
+ *               and destination property sets.
  *
  * \since This function is available since SDL 3.2.0.
  */