Update actions/checkout docs

[CannonLock]

Updates the actions/checkout doc section to demonstrate how to push a commit using the generated token.

My experience was that I came here because I needed to push with a app token so my CI would run after.

So an example of how to do that would have been more helpful then a example on how to prevent using this token to push.

Closing my other PR as I think this better addresses what I came to the docs looking for.

[Copilot]

Pull Request Overview

Updates the actions/checkout documentation to demonstrate pushing commits using the generated app token, replacing the previous example that showed how to prevent token persistence and use with prettier_action.

• Replaces the persist-credentials: false configuration and prettier_action usage with a direct git push example
• Adds steps showing file modification and committing changes using the app token
• Provides a more practical workflow example for users who need to push commits that trigger CI

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