Tracking progress on revamping documentation pages for the refactor of LM-Evaluation-Harness.


## Desired Pages

* [ ] YAML explainer
  * [ ] Explainer on filters + advanced features
  * [ ] Walkthrough start-to-finish of adding a new task to codebase
* [ ] Explaining registries + decorators
* [ ] model_guide.md for adding new model API
  * [ ] guide to writing an adapter to new advanced codebase (e.g. NeoX)
* [ ] Parallelism guide (?)