Start writing up developer documentation

[philpax]

We're getting more developers who are adding new implementations, which is great, but transformers and LLMs are complicated, and it'll require more than Rust knowledge to get to the bottom of why they aren't working.

We should assist new devs by writing up docs for where they can find out more about LLMs and how they work, as well as defining any terms or concepts that they're likely to encounter.

This is probably also a good place to discuss the idiosyncrasies of the ML ecosystem, including formats, conversions, tooling, and more.

Here's my initial list of LLM resources:

• https://jalammar.github.io/illustrated-gpt2/
• https://jalammar.github.io/illustrated-transformer/
• https://www.youtube.com/watch?v=kCc8FmEb1nY
• https://udlbook.github.io/udlbook/ (Chapter 12 specifically)