[models] Improve documentation of config files; Make ptbench config work again

src/ptbench/data/montgomery_shenzhen/fold_2.py

src/ptbench/data/montgomery_shenzhen/fold_3.py

src/ptbench/data/montgomery_shenzhen/fold_4.py

src/ptbench/data/montgomery_shenzhen/fold_5.py

src/ptbench/data/montgomery_shenzhen/fold_6.py

src/ptbench/data/montgomery_shenzhen/fold_7.py

src/ptbench/data/montgomery_shenzhen/fold_8.py

src/ptbench/data/montgomery_shenzhen/fold_9.py

src/ptbench/data/montgomery_shenzhen_indian/datamodule.py

src/ptbench/data/montgomery_shenzhen_indian/default.py

src/ptbench/data/montgomery_shenzhen_indian/fold_0.py

src/ptbench/data/montgomery_shenzhen_indian/fold_1.py

src/ptbench/data/montgomery_shenzhen_indian/fold_2.py

src/ptbench/data/montgomery_shenzhen_indian/fold_3.py

src/ptbench/data/montgomery_shenzhen_indian/fold_4.py

src/ptbench/data/montgomery_shenzhen_indian/fold_5.py

src/ptbench/data/montgomery_shenzhen_indian/fold_6.py

src/ptbench/data/montgomery_shenzhen_indian/fold_7.py

src/ptbench/data/montgomery_shenzhen_indian/fold_8.py

src/ptbench/data/montgomery_shenzhen_indian/fold_9.py