Documentation: Add guide geared towards devs working in prek-enabled repositories

[Feuermurmel]

There's a lot of documentation on how to use the prek CLI, how to configure it via prek.toml and .pre-commit-config.yaml, how to develop hooks, etc. But I can't find any good documentation geared towards developers that work in repositories that use prek, but that don't necessarily edit its configuration (same for pre-commit for that matter).

I'm thinking of a guide that could be linked to from a repository's README that explains how to set up prek for working on the repository and how to handle different scenarios (e.g. when a commit fails due to a hook).

I think it would be great if prek's documentation at https://prek.j178.dev included a guide that documents the following items:

• Setting up a repository that already uses prek (installing prek, prek install).
• Explain what happens when running git commit.
• What to do when a commit fails because a hook failed (i.e. look at error message, fix problems, re-add files, and try to commit again).
• What to do when a commit fails because a hook edited a file (i.e. optionally look at diff, re-add files, and try to commit again.).
• Mention some additional tips (e.g. prek run, git commit --no-verify).
• Optimally, the explanations would contain some example terminal sessions, so that users know what to expect and where to look for.