`C<>` not converted

```
✗ cat File.raku
#|(
    C<NICE>
)
sub thing {
    1;
}
```

Trying to escape the output of this command here in the ticket is miserable, but if you run:

```
✗ raku --doc=Markdown File.raku
```

Please note that the output literally includes `C<NICE>` and does not convert that to markdown.