video: Document that renderer lifetimes are tied to their associated windows

include/SDL3/SDL_render.h

@@ -2020,6 +2020,10 @@ extern DECLSPEC void SDLCALL SDL_DestroyTexture(SDL_Texture *texture);
  * If `renderer` is NULL, this function will return immediately after setting
  * the SDL error message to "Invalid renderer". See SDL_GetError().
  *
+ * Note that destroying a window implicitly destroys the associated renderer,
+ * so this should not be called if the window associated with the renderer has
+ * already been destroyed.
+ *
  * \param renderer the rendering context
  *
  * \since This function is available since SDL 3.0.0.

include/SDL3/SDL_video.h

@@ -2110,7 +2110,7 @@ extern DECLSPEC int SDLCALL SDL_SetWindowShape(SDL_Window *window, SDL_Surface *
 extern DECLSPEC int SDLCALL SDL_FlashWindow(SDL_Window *window, SDL_FlashOperation operation);
 
 /**
- * Destroy a window.
+ * Destroy a window. If the window has an associated SDL_Renderer, it will be implicitly destroyed as well.
  *
  * If `window` is NULL, this function will return immediately after setting
  * the SDL error message to "Invalid window". See SDL_GetError().