Cover approaches to evaluate LLM in a systematic way

> **Copied from upstream:** [dair-ai/Prompt-Engineering-Guide#126](https://github.com/dair-ai/Prompt-Engineering-Guide/issues/126)
> **Original author:** @omarsar
> **Originally created:** 2023-04-13

---

Cover approaches to evaluate LLM in a systematic way. Evaluation is getting more challenging with LLMs. It's a topic we should be covering in the guide as well. 