Remove blank XML doc tag in BaseLinkRelation.cs
Remove blank XML doc tag in BaseLinkRelation.cs

Remove empty `<returns>` tag in XML docs for `BaseLinkRelation.LoadAsync()` method.
AngleSharp/AngleSharp,AngleSharp/AngleSharp,AngleSharp/AngleSharp,AngleSharp/AngleSharp,AngleSharp/AngleSharp