Improve the testing documentation

[noklam]

Description

The new testing docs is hard to find (not mentioned) properly.

Currently, there is a "development" section with "automated testing"

The new test section that is created by @AhdraMeraliQB is in the "Tutorial section"

This should be mentioned early in the "automated testing" section.

Context

• Added mentions in the "Automated testing" section

For example, users is confused globals.yml is read for pipeline during kedro run but not when using pytest.

https://linen-slack.kedro.org/t/22301026/question-is-there-an-extra-step-required-to-run-pytest-with-#661646b5-a2e7-4b77-a3db-ab585f408793

[astrojuanlu]

Closing in favour of #4168, essentially the same issue? And that one has more discussion.