CI Visibility - Test configurations guide

[nachoBonafonte]

What does this PR do?

It adds a guide about how test configurations work and how to add custom configurations

Motivation

We want to explain our users how test configurations work

https://docs-staging.datadoghq.com/nachoBonafonte/CI-Visibility-Configurations-Guide/continuous_integration/guides/test_configurations

Additional Notes

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Reviewer checklist

• [ ] Review the changed files.
• [ ] Review the URLs listed in the Preview section.
• [ ] Check images for PII
• [ ] Review any mentions of "Contact Datadog support" for internal support documentation.

[github-actions[bot]]

Preview links (active after the build_preview check completes)

New or renamed files

• https://docs-staging.datadoghq.com/nachoBonafonte/CI-Visibility-Configurations-Guide/continuous_integration/guides/test_configurations

Modified Files

• https://docs-staging.datadoghq.com/nachoBonafonte/CI-Visibility-Configurations-Guide/continuous_integration/guides/

[alai97]

Thanks for reviewing @fermayo! I created an editorial review card for the Docs team: DOCS-3907.

[fermayo]

Thanks @alai97 !

[fermayo]

@kayayarai LGTM, but we are still waiting for this functionality to be released. We'll be removing the do-not-merge tag and ping you once it's ready to be merged. Thanks!

[nachoBonafonte]

Hi @kayayarai, the functionality has been released, we can merge this PR. Thanks!