Add discord channel

Author: jeromewu

README.md

@@ -6,6 +6,8 @@
 
 # ffmpeg.wasm
 
+[![stability-experimental](https://img.shields.io/badge/stability-experimental-orange.svg)](https://github.com/emersion/stability-badges#experimental)
+[![discord](https://dcbadge.vercel.app/api/server/NjGMaqqfm5?style=flat)](https://discord.gg/NjGMaqqfm5)
 [![Node Version](https://img.shields.io/node/v/@ffmpeg/ffmpeg.svg)](https://img.shields.io/node/v/@ffmpeg/ffmpeg.svg)
 [![Actions Status](https://github.com/ffmpegwasm/ffmpeg.wasm/workflows/CI/badge.svg)](https://github.com/ffmpegwasm/ffmpeg.wasm/actions)
 ![CodeQL](https://github.com/ffmpegwasm/ffmpeg.wasm/workflows/CodeQL/badge.svg)