Fix formatting in XAML attribute usage section

Author: Aurumaker72

xml/System.Windows/SystemParameters.xml

@@ -60,7 +60,7 @@
 
 <a name="xamlAttributeUsage_Border"></a>   
 ## XAML Attribute Usage  
- <*object property*="{ SystemParameters.Border`}`"/>  
+ `<*object property*="{SystemParameters.Border}"/>`  
 
  ]]></format>
         </remarks>