docs: improve test documentation
Description
This MR takes some of the content from my knowledge-sharing session and adds it to our developer documentation.
What CHANGELOG entry will this MR create?
-
fix:
Bug fix fixes - a user-facing issue in production - included in changelog -
feature:
New feature - a user-facing change which adds functionality - included in changelog -
BREAKING CHANGE:
(fix or feature that would cause existing functionality to change) - should bump major version, mentioned in the changelog -
None - other non-user-facing changes