Renderer: Empty `Name` column in Returns and Raises sections

[signekb]

When returns and raises don't have names, their sections are still rendered with a Name column. This is just an empty column.

This is similar to #389 (this is just when table_style is not description-list)

Example

From Shiny for Python

Expected behaviour

In this case, I would expect that there would no empty column named "Name". Something like:

## Raises
| Type | Description |
| -- | -- |
|TimeoutError | If the value does not change within timeout_secs. |