Download documentation needs updating, --repo_id required

[Sciumo]

Document says:

python scripts/download.py stabilityai/stablelm-base-alpha-3b

Actually required

python scripts/download.py --repo_id stabilityai/stablelm-base-alpha-3b

I could just make edits as I go along and send PR if you wish.

[carmocca]

Please do! You can also set as_positional=False in https://github.com/Lightning-AI/lit-parrot/blob/main/scripts/download.py#L35 and then it won't require --repo_id

[Sciumo]

Okay. I'll include some sanity and a fix as well.
Not sure how convert_hf_checkout.py ever worked since the check_valid_checkpoint_dir looks for lit_model.pth and lit_config.json doesn't even exist yet.

[carmocca]

This was fixed in #48. Thank you for reporting