Updated Container API (markdown)

Container-API.md

@@ -55,7 +55,7 @@ if _, err := container.New(
         ),
     ),
 ); err != nil {
-    panic(err)
+    return fmt.Errorf("container.New => %v", err)
 }
 ```
 
@@ -124,7 +124,7 @@ b, err := button.New("hello world", func() error {
 },
 )
 if err != nil {
-    return err
+    return fmt.Errorf("button.New => %v", err)
 }
 
 c, err := container.New(
@@ -132,7 +132,7 @@ c, err := container.New(
     container.PlaceWidget(b),
 )
 if err != nil {
-    return err
+    return fmt.Errorf("container.New => %v", err)
 }
 ```
 
@@ -157,7 +157,7 @@ b, err := button.New("hello world", func() error {
 },
 )
 if err != nil {
-    return err
+    return fmt.Errorf("button.New => %v", err)
 }
 
 c, err := container.New(
@@ -167,7 +167,7 @@ c, err := container.New(
     container.AlignVertical(align.VerticalTop),
 )
 if err != nil {
-    return err
+    return fmt.Errorf("container.New => %v", err)
 }
 ```
 
@@ -187,6 +187,33 @@ This section describes container options that specify its style or look.
 
 Containers don't have any borders by default, use one of the following options to instruct Termdash to draw a border around a container.
 
+[[/images/container-api/border_styles.gif|border_styles]]
+
+The following code shows two containers with different border styles as shown above:
+
+```go
+tb, err := termbox.New()
+if err != nil {
+    panic(err)
+}
+defer tb.Close()
+
+c, err := container.New(
+    t,
+    container.SplitVertical(
+        container.Left(
+            container.Border(linestyle.Light),
+        ),
+        container.Right(
+            container.Border(linestyle.Double),
+        ),
+    ),
+)
+if err != nil {
+    return fmt.Errorf("container.New => %v", err)
+}
+```
+
 #### [container.Border](https://godoc.org/github.com/mum4k/termdash/container#Border):
 
 The **container.Border** option is used to enable the border and specify its line style. Refer to the [[Linestyle API|linestyle-api]] for the available line styles.