Add documentation about frontend test categories to frontend guide
What does this MR do?
Clarify which test categories we have for frontend code.
What are the relevant issue numbers?
https://gitlab.com/gitlab-org/gitlab-ce/issues/48021
Does this MR meet the acceptance criteria?
-
Changelog entry added, if necessary -
Documentation created/updated -
Tests added for this feature/bug -
Conforms to the code review guidelines -
Conforms to the merge request performance guidelines -
Conforms to the style guides -
Conforms to the database guides
Edited by Inactive Account