message: Document what RENDERDOC_DevicePointer should be for D3D12
diff: @@ -370,6 +370,7 @@ The path follows the template set in :cpp:func:`SetCaptureFilePathTemplate` so i
  ``RENDERDOC_DevicePointer`` is a typedef to ``void *``. The contents of it are API specific:
  * For D3D11 it must be the ``ID3D11Device`` device object.
  + * For D3D12 it must be the ``ID3D12Device`` device object.
  * For OpenGL it must be the ``HGLRC`` or ``GLXContext`` context object.
  * For Vulkan it must be the dispatch table pointer within the ``VkInstance``. This is a pointer-sized value at the location pointed to by the ``VkInstance``. NOTE - this is not the actual ``VkInstance`` pointer itself. You can use the RENDERDOC_DEVICEPOINTER_FROM_VKINSTANCE helper macro defined in the renderdoc header to obtain this pointer from any VkInstance.
  