📚 [Documentation] - How to add new tests

[edwardchalstrey1]

Section of Documentation

Seshat Databank Admin -> Testing

Description of Improvement

Currently the testing page only explains how to run tests.

• It should be updated to explain how to add new tests to pytest.
• After Create tests for data sensibleness edwardchalstrey1/seshat#92 is complete, add info on these too
• Same for Set up tests for non-GIS models and views edwardchalstrey1/seshat#93
• Same for Refactor JavaScript in the application #25

Benefits of Improvement

Tests can be added in a consistent manner for new code

Additional Context

No response

Definition of Done

• The documentation improvement has been developed on a branch.
• The new branch has been tested in the Staging website.
• A pull request has been created for the new branch to be merged into the main branch.