Added exception information to SingleOrDefault (dotnet#4650)

Author: Ron Petrusha

xml/System.Linq/Enumerable.xml

@@ -8066,6 +8066,8 @@ From i As Integer In objects
         </remarks>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="source" /> or <paramref name="predicate" /> is <see langword="null" />.</exception>
+        <exception cref="T:System.InvalidOperationException">
+          More than one element satisfies the condition in <paramref name="predicate" />. </exception>    
       </Docs>
     </Member>
     <Member MemberName="Skip&lt;TSource&gt;">

xml/System.Linq/ImmutableArrayExtensions.xml

@@ -991,11 +991,12 @@
       </Parameters>
       <Docs>
         <typeparam name="T">The type of element contained by the collection.</typeparam>
-        <param name="immutableArray">To be added.</param>
+        <param name="immutableArray">The array.</param>
         <summary>  
 
  Returns the only element of the array, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence.</summary>
         <returns>The element in the array, or the default value if the array is empty.</returns>
+        <exception cref="T:System.InvalidOperationException"><paramref name="source" /> contains more than one element.</exception>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -1029,6 +1030,7 @@
  Returns the only element of a sequence that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition.</summary>
         <returns>The element if it satisfies the specified condition; otherwise the default element.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.InvalidOperationException">More than one element satisfies the condition in <paramref name="predicate" />. </exception>
       </Docs>
     </Member>
     <Member MemberName="ToArray&lt;T&gt;">

xml/System.Linq/ParallelEnumerable.xml

@@ -6740,6 +6740,7 @@
         <exception cref="T:System.OperationCanceledException">The query was canceled with the token passed in through <paramref name="WithCancellation" />.</exception>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="source" /> is a null reference (Nothing in Visual Basic).</exception>
+        <exception cref="T:System.InvalidOperationException"><paramref name="source" /> has more than one element. </exception>
         <exception cref="T:System.AggregateException">One or more exceptions occurred during the evaluation of the query.</exception>
       </Docs>
     </Member>