docs: add notifications.md with recommandation about notifications (#2979)

* docs: add demo argocd/grafana links

* docs: add notifications.md with recommandation about notifications

README.md

@@ -72,6 +72,7 @@ Organizations below are **officially** using Argo CD. Please send a PR with your
 ## Documentation
 
 To learn more about Argo CD [go to the complete documentation](https://argoproj.github.io/argo-cd/).
+Check live demo at https://cd.apps.argoproj.io/.
 
 ## Community Blogs and Presentations
 

docs/operator-manual/metrics.md

@@ -65,6 +65,7 @@ spec:
 
 ## Dashboards
 
-You can find an example Grafana dashboard [here](https://github.com/argoproj/argo-cd/blob/master/examples/dashboard.json)
+You can find an example Grafana dashboard [here](https://github.com/argoproj/argo-cd/blob/master/examples/dashboard.json) or check demo instance
+[dashboard](https://grafana.apps.argoproj.io).
 
 ![dashboard](../assets/dashboard.jpg)

docs/operator-manual/notifications.md

@@ -0,0 +1,14 @@
+# Notifications
+
+The notifications support is not bundled into the Argo CD itself. Instead of reinventing the wheel and implementing opinionated notifications system Argo CD leverages integrations
+with the third-party notification system. Following integrations are recommended:
+
+* To monitor Argo CD performance or health state of managed applications use [Prometheus Metrics](./metrics.md) in combination with [Grafana](https://grafana.com/),
+[Alertmanager](https://prometheus.io/docs/alerting/alertmanager/).
+* To notify the end-users of  Argo CD about events like application upgrades, user errors in application definition, etc use one of the following projects:
+    * [ArgoCD Notifications](https://github.com/argoproj-labs/argocd-notifications) - Argo CD specific notification system that continuously monitors Argo CD applications 
+    and aims to integrate with various notification services such as Slack, SMTP, Telegram, Discord, etc.
+    * [Argo Kube Notifier](https://github.com/argoproj-labs/argo-kube-notifier) - generic Kubernetes resource controller that allows monitoring any Kubernetes resource and sends a
+    notification when the configured rule is met.
+    * [Kube Watch](https://github.com/bitnami-labs/kubewatch) - a Kubernetes watcher that could publishes notification to Slack/hipchat/mattermost/flock channels. It watches the
+    cluster for resource changes and notifies them through webhooks.

mkdocs.yml

@@ -42,6 +42,7 @@ nav:
     - operator-manual/health.md
     - operator-manual/custom_tools.md
     - operator-manual/metrics.md
+    - operator-manual/notifications.md
   - User Guide:
     - user-guide/index.md
     - user-guide/application_sources.md