Docs: add pointer from tutorial to doc on tests priorities

[RoiTabach]

Before:

After:

The URL points to https://docs.elementary-data.com/guides/elementary-tests-configuration

[linear]

ELE-679 [DOCS] add pointer to test priorities from Tutorial on adding tests

Describe the problem
Users reading inside the tutorial don't understand there's a page that has a great clear explanation about the priorities of tests (test→model→global)

Describe the solution
Add a ref from the docs tutorial to the docs page

Describe the tests of the solution
don't think it's needed

Additional context
Happened in support here: https://elementary-community.slack.com/archives/C02CTC89LAX/p1681873690201069

Reviewer
Maayan

[github-actions]

👋 @RoiTabach
Thank you for raising your pull request.
Please make sure to add tests and document all user-facing changes.
You can do this by editing the docs files in this pull request.