Allow formatting breakdown charts with lambda expr

Relates to #252

examples/Console/Charts/Program.cs

@@ -19,10 +19,10 @@ namespace Charts
 
             // Render a breakdown chart
             AnsiConsole.WriteLine();
-            Render("Languages", new BreakdownChart()
+            Render("Languages used", new BreakdownChart()
                 .FullSize()
                 .Width(60)
-                .TagValueFormat("{0}%")
+                .ShowPercentage()
                 .AddItem("SCSS", 37, Color.Red)
                 .AddItem("HTML", 28.3, Color.Blue)
                 .AddItem("C#", 22.6, Color.Green)