Fix paths in training scripts

[zeakey]

The README currently suggests running these commands to get started:

pip install -r examples/requirements.txt
# download mipnerf_360 benchmark data
python examples/datasets/download_dataset.py
# run batch evaluation
bash examples/benchmarks/basic.sh

I assume these commands should be run from the project's root directory. If that’s correct, the paths in the bash scripts need to include the examples/ folder. Otherwise, I have to manually adjust the paths to make training work on my end.

If the commands aren’t meant to be run from the root, it’d be helpful to clearly specify where they should be executed.