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.