Nested dataclasses get top-level "config file" keys

[jder]

With this code:

@dataclass
class NestedConfig:
    something: str = field(default="something")

@dataclass
class ComputeConfig:
    nested: NestedConfig = field(default_factory=NestedConfig)

@dataclass
class Config:
    compute: ComputeConfig = field(default_factory=ComputeConfig)

The help includes a top level --nested str key for the config file for nested. I think it should probably be --compute.nested str or similar? I suspect we probably need to change this line to use child.dest rather than child.name?