[DOCS] not clear usage of test design in phase 4

[pautric]

What type of documentation issue is this?

Error or inaccuracy

Documentation location

https://bmad-code-org.github.io/bmad-method-test-architecture-enterprise/explanation/tea-overview/

What's the issue?

I have that

Phase 3: system-level test-design, then framework and ci.
Phase 4: per-epic test-design, optional atdd, then automate and optional test-review.

what is the deifference in usage of test-design for epic and for system level ?

Suggested improvement

give an example of the two usages

BMad Version (if applicable)

6.5