Clarify copilot-setup-steps.yml execution model in documentation (#59687)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: timrogers <116134+timrogers@users.noreply.github.com>
Co-authored-by: Tim Rogers <timrogers@github.com>
Co-authored-by: hubwriter <hubwriter@github.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: 4 people

content/copilot/how-tos/use-copilot-agents/coding-agent/customize-the-agent-environment.md

@@ -38,7 +38,8 @@ In addition, you can:
 
 You can customize {% data variables.product.prodname_copilot_short %}'s environment by creating a special {% data variables.product.prodname_actions %} workflow file, located at `.github/workflows/copilot-setup-steps.yml` within your repository.
 
-A `copilot-setup-steps.yml` file looks like a normal {% data variables.product.prodname_actions %} workflow file, but must contain a single `copilot-setup-steps` job. This job will be executed in {% data variables.product.prodname_actions %} before {% data variables.product.prodname_copilot_short %} starts working. For more information on {% data variables.product.prodname_actions %} workflow files, see [AUTOTITLE](/actions/using-workflows/workflow-syntax-for-github-actions).
+A `copilot-setup-steps.yml` file looks like a normal {% data variables.product.prodname_actions %} workflow file, but must contain a single `copilot-setup-steps` job. The steps in this job will be executed in {% data variables.product.prodname_actions %} before {% data variables.product.prodname_copilot_short %} starts working. For more information on {% data variables.product.prodname_actions %} workflow files, see [AUTOTITLE](/actions/using-workflows/workflow-syntax-for-github-actions).
+
 
 > [!NOTE]
 > The `copilot-setup-steps.yml` workflow won't trigger unless it's present on your default branch.