feat: update README

Author: Create-Peace

README.md

@@ -5,6 +5,41 @@
  npm install light-vue-tree
 ```
 
+```js
+<template>
+    <div class="base">
+        <VueTree
+        ref="tree1"
+        draggable
+        :treeData="treeData"
+        @on-drop="dropNode"
+        @on-selected-change="clickNode"
+        />
+    </div>
+</template>
+<script>
+import { treeData } from '../../assets/treeData'
+export default {
+    name: 'Base',
+    data () {
+        return {
+            treeData
+        }
+    },
+    methods: {
+        dropNode({ parentNode, targetNode, callback }) {
+            console.log("dropNode", parentNode, targetNode);
+            callback(targetNode);
+        },
+        clickNode (node) {
+            console.log('clickNode', node)
+        }
+    }
+}
+</script>
+
+```
+
 
 ## Advantages
 * Simple and very easy to use.