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

[JoshuaKGoldberg]

Bug Report Checklist

• I have pulled the latest main branch of the repository.
• I have searched for related issues 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