Added documentation for mouse handling in relative mode

Fixes https://github.com/libsdl-org/SDL/issues/11805

include/SDL3/SDL_mouse.h

@@ -359,6 +359,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_WarpMouseGlobal(float x, float y);
  * report continuous relative mouse motion even if the mouse is at the edge of
  * the window.
  *
+ * If you'd like to keep the mouse position fixed while in relative mode you can use SDL_SetWindowMouseRect(). If you'd like the cursor to be at a specific location when relative mode ends, you should use SDL_WarpMouseInWindow() before disabling relative mode.
+ *
  * This function will flush any pending mouse motion for this window.
  *
  * \param window the window to change.