docs(readme): add online

Author: ernado

README.md

@@ -2,7 +2,7 @@
 
 Telegram MTProto API client in Go for users and bots.
 
-[![Telegram: English chat](https://api.go-faster.org/badge/telegram/gotd_en?title=EN&v=1)](https://t.me/gotd_en) [![Telegram: Russian chat](https://api.go-faster.org/badge/telegram/gotd_ru?title=RU&v=1)](https://t.me/gotd_ru) [![Telegram: Chinese chat](https://api.go-faster.org/badge/telegram/gotd_zhcn?title=CN&v=1)](https://t.me/gotd_zhcn)
+[![Telegram: English chat](https://api.go-faster.org/badge/telegram/gotd_en?title=EN&v=1)](https://t.me/gotd_en) [![Telegram: Russian chat](https://api.go-faster.org/badge/telegram/gotd_ru?title=RU&v=1)](https://t.me/gotd_ru) [![Telegram: Chinese chat](https://api.go-faster.org/badge/telegram/gotd_zhcn?title=CN&v=1)](https://t.me/gotd_zhcn) [![Telegram: Online count](https://api.go-faster.org/badge/telegram/online?groups=gotd_ru&groups=gotd_en&groups=gotd_zhcn)](https://t.me/gotd_en)
 
 * [Examples](examples)
 * [Security policy](.github/SECURITY.md)