Discord link has been removed (percona#92)

README.md

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 [![Go Report Card](https://goreportcard.com/badge/github.com/percona/rds_exporter)](https://goreportcard.com/report/github.com/percona/rds_exporter)
 [![CLA assistant](https://cla-assistant.percona.com/readme/badge/percona/rds_exporter)](https://cla-assistant.percona.com/percona/rds_exporter)
 [![codecov.io Code Coverage](https://img.shields.io/codecov/c/github/percona/rds_exporter.svg?maxAge=2592000)](https://codecov.io/github/percona/rds_exporter?branch=main)
-[![Discord](https://img.shields.io/discord/808660945513611334?style=flat)](http://per.co.na/discord)
 
 An [AWS RDS](https://aws.amazon.com/ru/rds/) exporter for [Prometheus](https://github.com/prometheus/prometheus).
 It gets metrics from both [basic CloudWatch Metrics](https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/MonitoringOverview.html)