update readme

Author: huangshuwei

README.md

@@ -18,9 +18,18 @@ yarn add vue-lazy-container
 
 ## Usage
 
+Write the following in your mian.js：
+
+```javascript
+import VueLazyContainer from "vue-lazy-container";
+Vue.use(VueLazyContainer);
+```
+
+Example:
+
 ```javascript
 <template>
-  <vue-lazy-container tag-name="div" @change="intersectingChange">
+  <vue-lazy-container tag-name="div" @change="visibilityChange">
     <template v-if="isLoaded">
       <!-- your content -->
     </template>
@@ -35,8 +44,11 @@ export default {
     };
   },
   methods: {
-    intersectingChange(args) {
-      const { isIntersecting } = args;
+    // visibility change
+    visibilityChange(entry, observer) {
+      const { isIntersecting } = entry;
+
+      // visibility
       if (isIntersecting) {
         this.isLoaded = true;
         // you can ajax request or other logic
@@ -58,6 +70,6 @@ export default {
 
 **Event**
 
-| 事件名称 | 说明         | 回调参数          |
-| -------- | ------------ | ----------------- |
-| change  | 容器节点类型 | 观察者列表 |
+| 事件名称 | 说明         | 回调参数   |
+| -------- | ------------ | ---------- |
+| change   | 容器节点类型 | 观察者列表 |

package.json

@@ -1,6 +1,6 @@
 {
   "name": "vue-lazy-container",
-  "version": "1.0.0-beta.1",
+  "version": "1.0.0-beta.2",
   "description": "",
   "files": [
     "dist",