\docs\examples\custom_convert.py missing imports and Device object has to be AcceleratorDevice obj

[peterbaksa]

Bug

Just started using the example code in \docs\examples\custom_convert.py and find that there is missing:
from docling.datamodel.pipeline_options import AcceleratorDevice, AcceleratorOptions

and the object 'Device' looks that has to be object 'AcceleratorDevice' (Device object does not exists)

pipeline_options.accelerator_options = AcceleratorOptions(
        num_threads=4, device=Device.AUTO
    )

Docling version

Docling version: 2.15.1

Python version

Python version: 3.11.7

I will check the other example code, fix it and create PR.