Question: How to Guard a Modal?

Nobody has claimed this yet.

Is it correct that guards are not run for modal flows?

Edit: I found this in the comments.

```
/// Guards on the main router are **not** rerun when starting a flow
/// (a flow is its own transient state, not a navigation on the main
/// stack). The sub-router has no guards by default; pass [flowGuards]
/// if you need them.
```

Maybe this would be worth pointing out in the docs.

Edit 2: Are guards not run for the first route in a flow? It might also be worth adding the `reevaluateOn` parameter to running modal flows. Also, having a way to dismiss a modal flow with a guard would be useful.

Edit 3: Now I'm confused why sometimes you can add flowGuards and sometimes it's not an option.

Review the existing routing documentation and the modal-flow API entry points for guards, flowGuards, and reevaluateOn. Clarify when main-router and flow guards run, whether the first route is covered, and what options exist for guarded dismissal; done means the documented behavior and available parameters are unambiguous.

Written by the indexing model from the issue text.