Clarify that DataReceivedEventArgs.Data is null at end of stream

xml/System.Diagnostics/DataReceivedEventArgs.xml

@@ -114,7 +114,7 @@
       </ReturnValue>
       <Docs>
         <summary>Gets the line of characters that was written to a redirected <see cref="T:System.Diagnostics.Process" /> output stream.</summary>
-        <value>The line that was written by an associated <see cref="T:System.Diagnostics.Process" /> to its redirected <see cref="P:System.Diagnostics.Process.StandardOutput" /> or <see cref="P:System.Diagnostics.Process.StandardError" /> stream.</value>
+        <value>The line that was written by an associated <see cref="T:System.Diagnostics.Process" /> to its redirected <see cref="P:System.Diagnostics.Process.StandardOutput" /> or <see cref="P:System.Diagnostics.Process.StandardError" /> stream, or <see langword="null" /> if the end of the stream has been reached.</value>
         <remarks>
           <format type="text/markdown"><![CDATA[
 

xml/System.Diagnostics/Process.xml

@@ -1027,6 +1027,8 @@ The following code example creates a process that prints a file. It sets the <xr
 ## Remarks
  The <xref:System.Diagnostics.Process.ErrorDataReceived> event indicates that the associated <xref:System.Diagnostics.Process> has written a line that's terminated with a newline (carriage return (CR), line feed (LF), or CR+LF) to its redirected <xref:System.Diagnostics.Process.StandardError*> stream.
 
+ The event is also raised when the end of the redirected stream is reached. In that case, the <xref:System.Diagnostics.DataReceivedEventArgs.Data> property of the event handler's <xref:System.Diagnostics.DataReceivedEventArgs> is `null`.
+
  The event only occurs during asynchronous read operations on <xref:System.Diagnostics.Process.StandardError*>. To start asynchronous read operations, you must redirect the <xref:System.Diagnostics.Process.StandardError*> stream of a <xref:System.Diagnostics.Process>, add your event handler to the <xref:System.Diagnostics.Process.ErrorDataReceived> event, and call <xref:System.Diagnostics.Process.BeginErrorReadLine*>. Thereafter, the <xref:System.Diagnostics.Process.ErrorDataReceived> event signals each time the process writes a line to the redirected <xref:System.Diagnostics.Process.StandardError*> stream, until the process exits or calls <xref:System.Diagnostics.Process.CancelErrorRead*>.
 
 > [!NOTE]
@@ -3134,6 +3136,8 @@ If no main module is found, it could be because the process hasn't finished load
 ## Remarks
  The <xref:System.Diagnostics.Process.OutputDataReceived> event indicates that the associated <xref:System.Diagnostics.Process> has written a line that's terminated with a newline (carriage return (CR), line feed (LF), or CR+LF) to its redirected <xref:System.Diagnostics.Process.StandardOutput*> stream.
 
+ The event is also raised when the end of the redirected stream is reached. In that case, the <xref:System.Diagnostics.DataReceivedEventArgs.Data> property of the event handler's <xref:System.Diagnostics.DataReceivedEventArgs> is `null`.
+
  The event is enabled during asynchronous read operations on <xref:System.Diagnostics.Process.StandardOutput*>. To start asynchronous read operations, you must redirect the <xref:System.Diagnostics.Process.StandardOutput*> stream of a <xref:System.Diagnostics.Process>, add your event handler to the <xref:System.Diagnostics.Process.OutputDataReceived> event, and call <xref:System.Diagnostics.Process.BeginOutputReadLine*>. Thereafter, the <xref:System.Diagnostics.Process.OutputDataReceived> event signals each time the process writes a line to the redirected <xref:System.Diagnostics.Process.StandardOutput*> stream, until the process exits or calls <xref:System.Diagnostics.Process.CancelOutputRead*>.
 
 > [!NOTE]