add grid flowchart

lib/ui/grid/grid.js

@@ -439,7 +439,9 @@ const GridColumnDirection = {
 /**
  * Grid 控件基础类
  * 
- * <img src="./assets/grid-sample.png" alt="Grid Sample"/>
+ * <img src="./assets/grid-sample.png" alt="Grid Sample"/><br/>
+ * 函数调用流程图<br/>
+ * <img src="./assets/grid.jpg" alt="Grid"/>
  * @class
  * @example <caption>基础示例</caption>
  *  <div id="grid"></div>