update sandbox link

Author: vinz3872

README.md

@@ -13,7 +13,7 @@ A highly customizable vuejs tree viewer
 
 #### Example
 
-[codesandbox](https://codesandbox.io/s/vue-template-lmbyx)
+[codesandbox](https://codesandbox.io/s/vuejs-tree-sandbox-v3x-lmbyx)
 
 ## Getting Started
 
@@ -382,4 +382,4 @@ Methods Params:
 If you want to call any tree method, you need to get the instance.
 
 To get the tree instance you just need to be in the vue instance and use `this.$refs['my-tree-ref']`
-Then you can use a method like that: `this.$refs['my-tree-ref'].myMethod()`
+Then you can use a method like that: `this.$refs['my-tree-ref'].myMethod()`