convert-hf-to-gguf.py should have underscores.

[William-Wildridge]

In the wiki (https://github.com/unslothai/unsloth/wiki) for manually saving to gguf it has the line:

python llama.cpp/convert-hf-to-gguf.py FOLDER --outfile OUTPUT --outtype f16

This should be:

python llama.cpp/convert_hf_to_gguf.py FOLDER --outfile OUTPUT --outtype f16

Thanks!