Inline <seealso> not populating "See Also" section

### Inline `` does not populate the "See Also" section

### Functional impact

The reference won't appear in the "See Also" section.

### Minimal repro steps

Using docfx v2.20:

```C#
public class PopulatesSeeAlso
{ }

public class DoesNotPopulateSeeAlso
{ }

///
/// Also see .
///
///
public sealed class Test
{ }
```

### Expected result

All `` tags should appear in the "See Also" section, even if they are located inside a top-level tag, such as ``.

### Actual result

A top-level `` tag works as expected, but a `` tag appearing inside e.g. a `` tag will only appear in the "Summary" section, it won't (by itself) create a "See Also" section and it won't appear in the "See Also" section.