docs(evals): Updated docs for evals

[ssbushi]

Part of #985

Checklist (if applicable):

• PR title is following https://www.conventionalcommits.org/en/v1.0.0/
• Tested (manually, unit tested, etc.)
• Docs updated (updated docs or a docs bug required)

[mjchristy]

Overall, this LGTM. I wonder if we need to give them a RAG flow to evaluate, esp. given that we chose 'maliciousness'.

[ssbushi]

Overall, this LGTM. I wonder if we need to give them a RAG flow to evaluate, esp. given that we chose 'maliciousness'.

Maliciousness is not RAG specific.

[thedmail]

General observations:

• Informal tone is fine, but avoid "chatty". (E.g., "Now, we'll" or "Let's...")
• Avoid future tense and passive voice
• Always break lines at <= 80 cols

Please review second doc (plugin) and make similar edits, based on what I've done in the first doc.