[Request] Add Legend to AI Matrix

[dhru42]

Description

What: Create a legend for the LLM Performance matrix to clear up any confusion about the hierarchy of ratings
How: Show to readers that Excellent > Great > Good > Poor

Background & resources

• PRs:
• Issues/metas: Updates LLM performance matrix #6268
• Point of contact:
• Test environments:

Which documentation set does this change impact?

ESS and serverless

ESS release

8.16

Serverless release

N/A

Feature differences

N/A

API docs impact

What: Legend for LLM Performance matrix

Prerequisites, privileges, feature flags

N/A