Update DrillDown.md

Author: VimalaThirumalaikumar

MAUI/SunburstChart/DrillDown.md

@@ -137,11 +137,11 @@ sunburst.EnableDrillDown = true;
 SunburstToolbarSettings toolbarSettings = new SunburstToolbarSettings()
 {
     IconBrush = Colors.White,
-    ackground = new SolidColorBrush(Color.FromArgb("#2989F9")),
+    Background = new SolidColorBrush(Color.FromArgb("#2989F9")),
 };
 sunburst.ToolbarSettings = toolbarSettings;
 this.Content = sunburst;
 
 {% endhighlight %}
 
-{% endtabs %}
+{% endtabs %}