📝 Documentation: Flesh out docs for setting up bots and repo tokens

### Bug Report Checklist

- [X] I have pulled the latest `main` branch of the repository.
- [X] I have [searched for related issues](https://github.com/JoshuaKGoldberg/create-typescript-app/issues?q=is%3Aissue) and found none that matched my issue.

### Overview

Right now, https://github.com/JoshuaKGoldberg/create-typescript-app/blob/e3eef39d948d132ad42a0a9e1264296a732b5e6a/docs/Creation.md says what to do when creating a new repository. But:

* It's pretty terse and doesn't provide much detail
* Those steps are also applicable to _Initialization_ and _Migration_

I'll want to write a more informative docs page that walks users through these steps in more detail. Then that new page can be linked to in the _Creation_, _Initialization_, and _Migration_ pages.

### Additional Info

_No response_