Fix example description (#4654)

* Fix example description

* fix typo

* Update xml/System.Windows/Trigger.xml

Co-authored-by: Genevieve Warren <[email protected]>

Co-authored-by: Genevieve Warren <[email protected]>

Author: mairaw

xml/System.Windows/Trigger.xml

@@ -128,7 +128,7 @@
    
   
 ## Examples  
- The following example contains two triggers. The first changes the <xref:System.Windows.Controls.Control.Background%2A> property of a <xref:System.Windows.Controls.Button> when the <xref:System.Windows.UIElement.IsMouseOver%2A> property is `true`. The second changes the <xref:System.Windows.Controls.Control.Foreground%2A> property of a button when the <xref:System.Windows.Controls.Primitives.ButtonBase.IsPressed%2A> property is `true`. The <xref:System.Windows.Style.TargetType%2A> of the <xref:System.Windows.Style> is set to <xref:System.Windows.Controls.Button> and therefore there is no need to qualify the `Property` properties with the class name.  
+ The following example contains a trigger that changes the <xref:System.Windows.Controls.Control.Foreground%2A> property of a button when the <xref:System.Windows.Controls.Primitives.ButtonBase.IsPressed%2A> property is `true`. Because the <xref:System.Windows.Style.TargetType%2A> of the <xref:System.Windows.Style> is set to <xref:System.Windows.Controls.Button>, there's no need to qualify the `Property` properties, for example, `Property="IsPressed"`, with the class name.  
   
  [!code-xaml[BtnStyles#2](~/samples/snippets/csharp/VS_Snippets_Wpf/BtnStyles/CS/app.xaml#2)]