Add paramref in returns-comment. (dotnet#5334)

Author: ulfakerstedt

xml/System.Linq/Enumerable.xml

@@ -12197,7 +12197,7 @@ If `count` is not a positive number, this method returns an empty enumerable col
         <typeparam name="TSource">The type of the elements of <paramref name="source" />.</typeparam>
         <param name="source">An <see cref="T:System.Collections.Generic.IEnumerable`1" /> to create a <see cref="T:System.Collections.Generic.HashSet`1" /> from.</param>
         <summary>Creates a <see cref="T:System.Collections.Generic.HashSet`1" /> from an <see cref="T:System.Collections.Generic.IEnumerable`1" />.</summary>
-        <returns>A <see cref="T:System.Collections.Generic.HashSet`1" /> that contains values of type TSource selected from the input sequence.</returns>
+        <returns>A <see cref="T:System.Collections.Generic.HashSet`1" /> that contains values of type <paramref name="TSource" /> selected from the input sequence.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>