Markdown parsing

When parsing markdown, some times, elements are missing. For example, when parsing:
```- **Capital social**: 1 000,00 Euros```

docling returns only: ```- Capital social```

A simple solution for this case, would be to replace line 253:
```
snippet_text = str(first_child.children[0].children) # type: ignore
```

By this:
```
snippet_text = marko.md_renderer.MarkdownRenderer().render(first_child).strip() # type: ignore
```