docs: add discord server badge

README.md

@@ -1,4 +1,4 @@
-# Discordo · [![ci](https://github.com/ayn2op/discordo/actions/workflows/ci.yml/badge.svg)](https://github.com/ayn2op/discordo/actions/workflows/ci.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ayn2op/discordo)](https://goreportcard.com/report/github.com/ayn2op/discordo) [![license](https://img.shields.io/github/license/ayn2op/discordo?logo=github)](https://github.com/ayn2op/discordo/blob/master/LICENSE)
+# Discordo · [![discord](https://img.shields.io/discord/1297292231299956788?color=5865F2&logo=discord&logoColor=white)](https://discord.com/invite/VzF9UFn2aB) [![ci](https://github.com/ayn2op/discordo/actions/workflows/ci.yml/badge.svg)](https://github.com/ayn2op/discordo/actions/workflows/ci.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/ayn2op/discordo)](https://goreportcard.com/report/github.com/ayn2op/discordo) [![license](https://img.shields.io/github/license/ayn2op/discordo?logo=github)](https://github.com/ayn2op/discordo/blob/master/LICENSE)
 
 Discordo is a lightweight, secure, and feature-rich Discord terminal client. Heavily work-in-progress, expect breaking changes.