Document that multiple files can be included in analysis options, in analyzer 3.7 maybe

[srawlins]

The analyzer will start recognizing a list of included analysis options, where it currently supports including a single file. See dart-lang/sdk#47256

E.g.

include:
  - one.yaml
  - ../../two.yaml
  - package:foo/three.yaml

The "Customizing static analysis" page doesn't mention "include" a lot, or specify it. So we've got a blank slate to start at :D. We can specify how a chain, or directed graph, of "includes" works.

[srawlins]

@parlough is this something I can start working on now? Dart 3.6 isn't out yet, but this feature is available starting with Dart 3.7... Is there an example of wording like this?

[parlough]

I'd recommend a new section that focuses on include and starting with an example including a single file. Then a second part of that section can discuss multiple files, and that section could end with a version note similar to the following:

:::version-note
Support for including multiple files was added in Dart 3.7.
:::