Nested resource argument description collides with top level argument of the same name

### What happened?

I have a Terraform resource with the following argument reference pattern, where one argument (named `my_variable`) appears 2 times in 2 different contexts with different descriptions, once in the top level and once in a nested block:

```
## Argument Reference

- `my_variable` - Description A.
- `my_list` - List of nested configs.
- `my_variable` - Description B.
```

Once Crossplane files are generated, **all instances of `my_variable` in the generated files have the `Description A.`, even the nested ones**. This is true for the CRDs, the provider-metadata, and zz_*.go files.

Additionally, in the provider-metadata.yaml argumentDocs, `my_variable` appears only once (it appears arguments are listed in alphabetical order with no notion of nesting, so the second occurrence is completely overridden).

### Expected behaviour

Nested arguments are handled in their specific context, and the generated files properly handle their descriptions independently.