Added examples on how to use the Border element

Source/QuestPDF.Examples/BorderExamples.cs

@@ -0,0 +1,68 @@
+using NUnit.Framework;
+using QuestPDF.Examples.Engine;
+using QuestPDF.Fluent;
+using QuestPDF.Helpers;
+
+namespace QuestPDF.Examples
+{
+    public class BorderExamples
+    {
+        [Test]
+        public void Border_Simple()
+        {
+            RenderingTest
+                .Create()
+                .PageSize(200, 150)
+                .ProduceImages()
+                .ShowResults()
+                .Render(container =>
+                {
+                    container
+                        .Padding(25)
+                        
+                        .BorderLeft(6)
+                        .BorderTop(9)
+                        .BorderRight(12)
+                        .BorderBottom(15)
+                        .BorderColor(Colors.Green.Darken3)
+                        
+                        .Background(Colors.Grey.Lighten2)
+                        
+                        .AlignCenter()
+                        .AlignMiddle()
+                        .Text("Text")
+                        .FontSize(20);
+                });
+        }
+        
+        [Test]
+        public void Border_DifferentColors()
+        {
+            RenderingTest
+                .Create()
+                .PageSize(200, 150)
+                .ProduceImages()
+                .ShowResults()
+                .Render(container =>
+                {
+                    container
+                        .Padding(25)
+                        
+                        .BorderTop(5)
+                        .BorderColor(Colors.Blue.Darken1)
+                        
+                        .Container()
+                        
+                        .BorderBottom(5)
+                        .BorderColor(Colors.Green.Darken1)
+                        
+                        .Background(Colors.Grey.Lighten2)
+                        
+                        .AlignCenter()
+                        .AlignMiddle()
+                        .Text("Text")
+                        .FontSize(20);
+                });
+        }
+    }
+}