Add remark to Directory.Move about exception thrown in all platforms (#2358)

* Add remark to Directory.Move about exception thrown in all platforms.

* Add remark to Directory.Move about exception thrown in all platforms.

* Apply suggestions from code review

Suggestions provided by rpetrusha.

Co-Authored-By: carlossanlop <1175054+carlossanlop@users.noreply.github.com>

* Update Directory.xml

Suggested by rpetrusha:
- The note should be placed in the Remarks section, not the Examples section.
- It would be useful to add "See the Note in the Remarks section." to line 3486.

Author: carlossanlop

xml/System.IO/Directory.xml

@@ -3468,22 +3468,25 @@ Directory::CreateDirectory("Public\\Html");
  Trailing spaces are removed from the end of the path parameters before moving the directory.  
   
  For a list of common I/O tasks, see [Common I/O Tasks](~/docs/standard/io/common-i-o-tasks.md).  
-  
+
+
+> [!NOTE]
+>  Starting with .NET Core 3.0, the `Move` method throws an <xref:System.IO.IOException> in all platforms when the `destDirName` already exists. In .NET Core 2.2 and previous versions, the exception was only thrown on Windows, and other platforms could either fail or overwrite the `destDirName`. See [C++ rename](https://linux.die.net/man/2/rename).
    
   
 ## Examples  
  The following example demonstrates how to move a directory and all its files to a new directory. The original directory no longer exists after it has been moved.  
   
  [!code-csharp[System.IO.Directory#14](~/samples/snippets/csharp/VS_Snippets_CLR_System/system.IO.Directory/CS/class6.cs#14)]
  [!code-vb[System.IO.Directory#14](~/samples/snippets/visualbasic/VS_Snippets_CLR_System/system.IO.Directory/VB/class6.vb#14)]  
-  
+
  ]]></format>
         </remarks>
-        <exception cref="T:System.IO.IOException">An attempt was made to move a directory to a different volume.  
+        <exception cref="T:System.IO.IOException">An attempt was made to move a directory to a different volume.
 
  -or-  
 
- <paramref name="destDirName" /> already exists.  
+ <paramref name="destDirName" /> already exists. See the Note in the Remarks section.
 
  -or-  
 
@@ -4143,4 +4146,4 @@ Directory::CreateDirectory("Public\\Html");
       </Docs>
     </Member>
   </Members>
-</Type>
+</Type>