Add Twitter badge (#829)

* Add Twitter badge

* Remove extra line break

README.md

@@ -10,6 +10,7 @@
 **[The rrweb documentary (in Chinese, with English subtitles)](https://www.bilibili.com/video/BV1wL4y1B7wN?share_source=copy_web)**
 
 [![Join the chat at slack](https://img.shields.io/badge/slack-@rrweb-teal.svg?logo=slack)](https://join.slack.com/t/rrweb/shared_invite/zt-siwoc6hx-uWay3s2wyG8t5GpZVb8rWg)
+[![Twitter Follow](https://img.shields.io/badge/twitter-@rrweb__io-teal.svg?logo=twitter)](https://twitter.com/rrweb_io)
 ![total gzip size](https://img.badgesize.io/https://cdn.jsdelivr.net/npm/rrweb@latest/dist/rrweb.min.js?compression=gzip&label=total%20gzip%20size)
 ![recorder gzip size](https://img.badgesize.io/https://cdn.jsdelivr.net/npm/rrweb@latest/dist/record/rrweb-record.min.js?compression=gzip&label=recorder%20gzip%20size)
 [![](https://data.jsdelivr.com/v1/package/npm/rrweb/badge)](https://www.jsdelivr.com/package/npm/rrweb)