docs(alerting): removed a repetition of a word (grafana#52376)

removed a repetition of a word in doc

Author: medamineamara

docs/sources/alerting/_index.md

@@ -11,7 +11,7 @@ weight: 114
 
 Grafana Alerting allows you to learn about problems in your systems moments after they occur. Create, manage, and take action on your alerts in a single, consolidated view, and improve your team’s ability to identify and resolve issues quickly.
 
-Grafana Alerting is available for for Grafana OSS, Grafana Enterprise, or Grafana Cloud. With Mimir and Loki alert rules you can run alert expressions closer to your data and at massive scale, all managed by the Grafana UI you are already familiar with.
+Grafana Alerting is available for Grafana OSS, Grafana Enterprise, or Grafana Cloud. With Mimir and Loki alert rules you can run alert expressions closer to your data and at massive scale, all managed by the Grafana UI you are already familiar with.
 
 Watch this video to learn more about Grafana Alerting: {{< vimeo 720001629 >}}