Add documentation for existing tests

Pipeline is running a range of tests with the new API.
Add documentation explaining each of them in detail to make sure new users or developers can understand details such as what the test is about, possible test results, sub-tests, and can use this information for test analysis, post-processing, or even adding new tests.

- [ ] Add documentation
- [ ] Deploy to `kernelci.org/docs` (https://kernelci.org/docs/tests/ looks like a good place for such information)
- [ ] Update Kernelci tests links on https://github.com/kernelci/kcidb/blob/main/tests.yaml

Start with tests.yaml, the existing tests documentation at kernelci.org/docs/tests/, and the pipeline's current test definitions to inventory the tests exposed by the new API. Document each test's purpose, possible results, sub-tests, and analysis or extension guidance; done includes deploying the documentation and updating the KernelCI test links in tests.yaml.

Written by the indexing model from the issue text.