update readme

README.md

@@ -135,15 +135,21 @@ No problem. With the help of ES6 Template literals, we can customize the any com
 
 - [I want to position node in specific level. How can i do that ?](https://dabeng.github.io/OrgChart/level-offset.html)
 
-You need the solution based on new datasource structure with levelOffset data prop + callback createNode() + CSS custom properties(variables)
+![level-offset](http://dabeng.github.io/OrgChart/img/level-offset.png)
+
+You need the solution based on new datasource structure with **levelOffset data prop** + callback createNode() + CSS custom properties(variables)
 
 - [I want a orgchart with nodes of different widths](https://dabeng.github.io/OrgChart/nodes-of-different-widths.html)
 
+![nodes-of-different-widths](http://dabeng.github.io/OrgChart/img/nodes-of-different-widths.png)
+
 - [I want to drag&drop in the hybrid chart](https://dabeng.github.io/OrgChart/drag-drop-hybrid-chart.html)
 
 - [ I only want specific children of a certain branch of the chart to be displayed as vertical. Is it possible to set VerticalLevel by data?](https://dabeng.github.io/OrgChart/isHybrid.html)
 
-isVertical data property is designed for your use case. Once a node has a "isVertical" prop with truthy value, its descendant nodes will be arranged vertically.
+![isHybrid](http://dabeng.github.io/OrgChart/img/isHybrid.png)
+
+**isVertical data property** is designed for your use case. Once a node has a "isVertical" prop with truthy value, its descendant nodes will be arranged vertically.
 
 ### how to start up demos locally