chore: add information about high availability of NATS servers (kyma-…

…project#365)

* chore: add information about high availability of NATS servers

* updated

* Update 02-configuration.md

docs/user/02-configuration.md

@@ -25,6 +25,10 @@ Use the following sample CRs as guidance. Each can be applied immediately when y
 - [Minimal CR](https://github.com/kyma-project/nats-manager/blob/main/config/samples/minimal.yaml#L1)
 - [Full spec CR](https://github.com/kyma-project/nats-manager/blob/main/config/samples/nats-full-spec.yaml#L1)
 
+## High availability
+
+For high availability, the NATS servers must be set up across different availability zones for uninterrupted operation and uptime. NATS Manager deploys the NATS servers in the availability zones where your Kubernetes cluster has Nodes. If the Kubernetes cluster has Nodes distributed across at least three availability zones, NATS Manager automatically distributes the NATS servers across these availability zones. If the Kubernetes cluster doesn’t have Nodes distributed across at least three availability zones, high availability is compromised.
+
 ## Reference
 
 <!-- The table below was generated automatically -->