:book: Updated CI-Test description

[Jordin221]

Modified description to detail test only considers successes.

What kind of change does this PR introduce?

Updated documentation of CI-Test check description to highlight it only considers successes.

• [x] PR title follows the guidelines defined in our pull request documentation

What is the current behavior?

Description does not mention that this check only considers successes.

What is the new behavior (if this is a feature change)?**

The description now mentions that the check only considers successes.

• [ ] Tests for the changes have been added (for bug fixes/features)

Which issue(s) this PR fixes

Fixes #3616

Special notes for your reviewer

Does this PR introduce a user-facing change?

For user-facing changes, please add a concise, human-readable release note to the release-note

(In particular, describe what changes users might need to make in their application as a result of this pull request.)

NONE