Update README.md

Author: gkorland

README.md

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 # RedisJSON Python Client
 
 [![Forum](https://img.shields.io/badge/Forum-RedisJSON-blue)](https://forum.redislabs.com/c/modules/redisjson)
-[![Gitter](https://badges.gitter.im/RedisLabs/RedisJSON.svg)](https://gitter.im/RedisLabs/RedisJSON?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)
+[![Discord](https://img.shields.io/discord/697882427875393627?style=flat-square)](https://discord.gg/QUkjSsk)
 
 rejson-py is a package that allows storing, updating and querying objects as
 JSON documents in a [Redis](https://redis.io) database that is extended with the