Document System.Random.NextBytes (#3638)

* Document System.Random.NextBytes

* suggestions by Jozkee and gewarren

Co-Authored-By: David Cantu <[email protected]>
Co-Authored-By: Genevieve Warren <[email protected]>

Author: 3 people

xml/System/Random.xml

@@ -706,7 +706,7 @@ The following example uses the parameterless constructor to instantiate three <x
         <Parameter Name="buffer" Type="System.Byte[]" />
       </Parameters>
       <Docs>
-        <param name="buffer">An array of bytes to contain random numbers.</param>
+        <param name="buffer">The array to be filled with random numbers.</param>
         <summary>Fills the elements of a specified array of bytes with random numbers.</summary>
         <remarks>
           <format type="text/markdown"><![CDATA[  
@@ -761,9 +761,17 @@ The following example uses the parameterless constructor to instantiate three <x
         <Parameter Name="buffer" Type="System.Span&lt;System.Byte&gt;" Index="0" FrameworkAlternate="netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="buffer">To be added.</param>
-        <summary>To be added.</summary>
-        <remarks>To be added.</remarks>
+        <param name="buffer">The array to be filled with random numbers.</param>
+        <summary>Fills the elements of a specified span of bytes with random numbers.</summary>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Each element of the span of bytes is set to a random number greater than or equal to 0 and less than or equal to <xref:System.Byte.MaxValue>.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="NextDouble">