Update IReadOnlySet`1.xml

Fixed IsSupersetOf return comment

Author: hnesk

xml/System.Collections.Generic/IReadOnlySet`1.xml

@@ -193,7 +193,7 @@
         <param name="other">The collection to compare to the current set.</param>
         <summary>Determine whether the current set is a super set of a specified collection.</summary>
         <returns>
-          <see langword="true" /> if the current set is a subset of other; otherwise <see langword="false" />.</returns>
+          <see langword="true" /> if the current set is a super set of other; otherwise <see langword="false" />.</returns>
         <remarks>To be added.</remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="other" /> is <see langword="null" />.</exception>