gguf.md: add sharding to naming convention

[mofosyne]

As per #822 (review) suggestion, adding support for sharding in naming convention.

Was a bit worried about if -of- is going to be annoying to parse, but I think it's not too much to ask programmers to check if XXXXX-of-XXXXX exist first and delete that before processing the rest from right to left by splitting by -. The requirement for 5 digits and -of- is pretty distinctive anyway.

@ggerganov this is a PR to add this idea on behalf of @mishig25 and based on checking hf it appears to be a common enough convention already e.g. vicuna.gguf

[mishig25]

LGTM! 🚀

[mofosyne]

Minor commit to address Justine's observation that

One of the mistakes I made in my upload scripts, was sometimes not choosing exactly what the original project called itself, casing and all. So as a result, I've been having a hard time consolidating my upload scripts.

So recommended that the model, version and expert count be derived from gguf metadata. This consistency should hopefully reduce surprises when creating upload scripts by making the filename generation a bit more repeatable.

[julien-c]

love it!

[mofosyne]

@ggerganov ready to merge

[mofosyne]

Still ready for review @ggerganov , just added a regex example and tighten up the description.

[mofosyne]

@mishig25 it's now merged in, so you can use it now :)

[mishig25]

@mofosyne Awesome!