`nomad fmt` fails against topology segments in volume examples

### Nomad version

```
$ nomad version
Nomad v1.4.2 (039d70eeef5888164cad05e7ddfd8b6f8220923b)
```

### Operating system and Environment details

n/a

### Issue

I ran `nomad fmt` against the volume example at https://developer.hashicorp.com/nomad/docs/other-specifications/volume, and it failed:

```
Error: Argument definition required

on example_volume.nomad line 27:
27: topology { segments { "rack" = "R2" } }

A single-line block definition can contain only a single argument. If you meant to define argument "segments", use an equals sign to assign it a
value. To define a nested block, place it on a line of its own within its parent block.

Error: Argument definition required

on example_volume.nomad line 31:
31: topology { segments { "rack" = "R1", "zone" = "us-east-1a"} }

A single-line block definition can contain only a single argument. If you meant to define argument "segments", use an equals sign to assign it a
value. To define a nested block, place it on a line of its own within its parent block.
```

If I change the topology definition to use `segments =`, i.e.

```
preferred {
topology {
segments = { "rack" = "R1", "zone" = "us-east-1a"}
}
}
```

then `nomad fmt` completes successfully; but since the official examples use the one-line format, I don't know if the examples are misformatted or if `nomad fmt` is misbehaving.

Start with the volume example at the linked Nomad documentation and reproduce the failure using `nomad fmt` on `example_volume.nomad`, especially lines 27 and 31. Compare the one-line `topology { segments { ... } }` form with the working `segments =` form; done means the official example and formatter behavior agree, with the appropriate example or formatter issue corrected.

Written by the indexing model from the issue text.