correctly refer to "using directives"

Address incorrect use of ["using statement"](https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/using-statement) to refer to a ["using directive"](https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/using-directive).

Author: mrlacey

docs/extensibility/walkthrough-saving-user-settings-on-a-start-page.md

@@ -73,7 +73,7 @@ For more information about how to persist settings, see [Extending User Settings
 
      This step opens *MyControl.xaml.cs*, and creates a stub handler for the `Button_Click` event.
 
-2. Add the following `using` statements to the top of the file.
+2. Add the following `using` directives to the top of the file.
 
      [!code-csharp[StartPageDTE#11](../extensibility/codesnippet/CSharp/walkthrough-saving-user-settings-on-a-start-page_1.cs)]
 
@@ -193,4 +193,4 @@ You can modify this user control to save and retrieve any number of custom setti
 ## See also
 
 - <xref:EnvDTE80.DTE2?displayProperty=fullName>
-- [Adding Visual Studio commands to a Start Page](../extensibility/adding-visual-studio-commands-to-a-start-page.md)
+- [Adding Visual Studio commands to a Start Page](../extensibility/adding-visual-studio-commands-to-a-start-page.md)