completed extend-controls docs

doc/source/handycontrol/extend_controls/dashedBorder/index.md

@@ -0,0 +1,35 @@
+---
+title: DashedBorder 虚线边框
+---
+
+一种装饰元素，可提供虚线边框，以实现某些特殊效果.
+
+```cs
+public class DashedBorder : Decorator
+```
+
+# 属性
+
+|属性|描述|默认值|备注|
+|-|-|-|-|
+|BorderThickness|边框粗细|||
+|BorderDashThickness|边框虚线粗细|0||
+|Padding|内边距|||
+|CornerRadius|圆角|||
+|BorderBrush|边框颜色|||
+|Background|背景色|||
+|BorderDashArray|边框虚线数组|||
+|BorderDashCap|边框虚线线帽样式|PenLineCap.Flat||
+|BorderDashOffset|边框虚线偏移|0|||
+
+# 案例
+
+```xml
+<hc:DashedBorder Width="100" Height="100" BorderDashThickness="2" BorderBrush="Black" BorderDashArray="3, 1" CornerRadius="0,50,0,0"/>
+```
+
+![DashedBorder](https://raw.githubusercontent.com/HandyOrg/HandyOrgResource/master/HandyControl/Doc/extend_controls/DashedBorder.png)
+
+{% note warning %}
+当需要设置边框粗细时要注意，如果4个圆角数值一致，请使用 `BorderThickness`，否则请使用 `BorderDashThickness`
+{% endnote %}