Improve documentation

[aaronsantiago]

There is a lot going on in this repo and a couple things I've tripped on trying to get working for myself:

• What are the valid parameters for the server arguments, and what do they do?
• How does one use locally downloaded models instead of the ones hosted on Huggingface?

[hafriedlander]

I think documenting engines.yaml is the most pressing, the server arguments do have some documentation when you use --help (although admittedly not much). There's an update coming soon that will significantly increase complexity of engines.yaml too.

Once that's up it'd be great if someone volunteered and had a first stab. Otherwise I'll get to it eventually.

[hafriedlander]

Just updating that the new engines.yaml includes a lot more documentation as comments. Hopefully it's a bit improved now (although I'll leave this open as there's still plenty of room for improvement).