Fix wpf overview styles xaml (#209)

dotnet-desktop-guide/framework/wpf/introduction-to-wpf.md

@@ -513,7 +513,9 @@ Styles enable developers and designers to standardize on a particular appearance
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
     x:Class="SDKSample.StyleWindow"
     Title="Styles">
-  <!-- Style that will be applied to all buttons -->
+    
+    <Window.Resources>
+        <!-- Style that will be applied to all buttons for this window -->
         <Style TargetType="{x:Type Button}">
             <Setter Property="Background" Value="Orange" />
             <Setter Property="BorderBrush" Value="Crimson" />
@@ -521,6 +523,9 @@ Styles enable developers and designers to standardize on a particular appearance
             <Setter Property="FontWeight" Value="Bold" />
             <Setter Property="Margin" Value="5" />
         </Style>
+    </Window.Resources>
+    <StackPanel>
+
         <!-- This button will have the style applied to it -->
         <Button>Click Me!</Button>
 
@@ -529,6 +534,8 @@ Styles enable developers and designers to standardize on a particular appearance
 
         <!-- This button will have the style applied to it -->
         <Button>Click Me!</Button>
+        
+    </StackPanel>
 </Window>
 ```