Names are not picked up by Documenter.jl

Any globals inserted into my main module are not automatically rendered when I use [`autodocs`](https://juliadocs.github.io/Documenter.jl/stable/man/syntax/#@autodocs-block)

MWE is a package like:
```julia
module Example
using Reexport

@reexport module Sub
export greet
greet(x) = "Hello $x"
end
end
```

With `docs/make.jl`
```julia
using Documenter

makedocs(;
sitename = "Example",
modules = [Example]
)
```
and `docs/src/index.md`:
```md
# Example.jl

``\`@meta
CurrentModule = Example
``\`

``\`@autodocs
Modules = [Example]
Order = [:function, :type]
``\`

```

Adding
```julia
Modules = [Example, Example.Sub]
```
does not help

Reproduce the example using docs/make.jl and docs/src/index.md, with the Example and Example.Sub modules shown in the issue. Start by tracing how the re-exported module is exposed to Documenter.jl's @autodocs block. Done means autodocs renders greet from the main module without explicitly adding Example.Sub.

Written by the indexing model from the issue text.