Update docs for Random.GetItems

Author: stephentoub

xml/System/Random.xml

@@ -299,7 +299,7 @@ The following example uses the parameterless constructor to instantiate three <x
         <param name="length">The length of array to return.</param>
         <summary>Creates an array populated with items chosen at random from the provided set of choices.</summary>
         <returns>An array populated with random items.</returns>
-        <remarks>The method uses <see cref="M:System.Random.Next(System.Int32)" /> to select items randomly from <paramref name="choices" /> by index. This is used to populate a newly-created array.</remarks>
+        <remarks>The method uses other methods from this instance to select items randomly from <paramref name="choices" /> by index. This is used to populate a newly-created array. If a seed was provided to create the instance, the results of this method are deterministic, however changes in the algorithm employed may yield different results between major versions of .NET.</remarks>
         <exception cref="T:System.ArgumentException">
           <paramref name="choices" /> is empty.</exception>
         <exception cref="T:System.ArgumentOutOfRangeException">
@@ -363,7 +363,7 @@ The following example uses the parameterless constructor to instantiate three <x
         <param name="choices">The items to use to populate the span.</param>
         <param name="destination">The span to be filled with items.</param>
         <summary>Fills the elements of a specified span with items chosen at random from the provided set of choices.</summary>
-        <remarks>The method uses <see cref="M:System.Random.Next(System.Int32)" /> to select items randomly from <paramref name="choices" /> by index and populate <paramref name="destination" />.</remarks>
+        <remarks>The method uses other methods on this instance to select items randomly from <paramref name="choices" /> by index and populate <paramref name="destination" />.  If a seed was provided to create the instance, the results of this method are deterministic, however changes in the algorithm employed may yield different results between major versions of .NET.</remarks>
         <exception cref="T:System.ArgumentException">
           <paramref name="choices" /> is empty.</exception>
       </Docs>
@@ -413,7 +413,7 @@ The following example uses the parameterless constructor to instantiate three <x
         <param name="length">The length of array to return.</param>
         <summary>Creates an array populated with items chosen at random from the provided set of choices.</summary>
         <returns>An array populated with random items.</returns>
-        <remarks>The method uses <see cref="M:System.Random.Next(System.Int32)" /> to select items randomly from <paramref name="choices" /> by index. This is used to populate a newly-created array.</remarks>
+        <remarks>The method uses other methods on this instance to select items randomly from <paramref name="choices" /> by index. This is used to populate a newly-created array. If a seed was provided to create the instance, the results of this method are deterministic, however changes in the algorithm employed may yield different results between major versions of .NET.</remarks>
         <exception cref="T:System.ArgumentException">
           <paramref name="choices" /> is empty.</exception>
         <exception cref="T:System.ArgumentNullException">