chore: update README

Author: chengpeiquan

README.en.md

@@ -14,8 +14,6 @@
 
 Only 3 kB, this plugin base on the Baidu analytics, it can help you quickly to collect the page views on your website, including single page web application.
 
-Projects using this plugin need to be import [Vue Router](https://router.vuejs.org/) .
-
 >Since the version v2.0.0, it supports the Vue 3.0, and is compatible with the Vue 2.0, you can see the live demo to learn more.<br>If you haven’t started using Vue 3.0, welcome to read the tutorial [learning Vue3](https://vue3.chengpeiquan.com/) .
 
 ## Features
@@ -24,7 +22,7 @@ Projects using this plugin need to be import [Vue Router](https://router.vuejs.o
 
 * Support the deployment of multiple site IDs and corresponding data reporting.
 
-* Supports automatic reporting of PV data generated by route switching (supports hash mode and history mode).
+* Supports automatic reporting of PV data generated by route switching (This feature need [Vue Router](https://router.vuejs.org/), It can support hash mode and history mode).
 
 * Support manual submission of page views reports.
 
@@ -60,7 +58,7 @@ Vue 3.0 ：[vue-baidu-analytics demo for Vue 3.x](https://analyticsjs.github.io/
 
 Option|Required|Type|Description
 :-:|:-:|:-:|-
-router|true|object|Vue Router, this plugin is based on Vue Router.
+router|false|object|Vue Router(It is optional since v2.2.0.)
 siteIdList|true|string[]|The site ids for Baidu analytics, if only one site needs to be reported, just keep one item in the array.
 isDebug|false|boolean|if `true`, it will open the debug mode，you can see the log in the console.
 
@@ -308,6 +306,10 @@ this.$pushBAIDU.event(
 );
 ```
 
+## CHANGELOG
+
+See：[releases](https://github.com/analyticsjs/vue-baidu-analytics/releases)
+
 ## License
 
 [MIT License](https://github.com/analyticsjs/vue-baidu-analytics/blob/master/LICENSE) © 2019 [chengpeiquan](https://github.com/chengpeiquan)