CSPL-4212 Documentation update on app installation and Splunk restart

Author: kasiakoziol

docs/IndexIngestionSeparation.md

@@ -382,6 +382,14 @@ In the following example, the dashboard presents ingestion and indexing data in
 
 - [kube-prometheus-stack](https://github.com/prometheus-community/helm-charts/tree/main/charts/kube-prometheus-stack)
 
+# App Installation for Ingestor Cluster Instances
+
+Application installation is supported for Ingestor Cluster instances. However, as of now, applications are installed using local scope and if any application requires Splunk restart, there is no automated way to detect it and trigger automatically via Splunk Operator. 
+
+Therefore, to be able to enforce Splunk restart for each of the Ingestor Cluster pods, it is recommended to add/update IngestorCluster CR annotations/labels and apply the new configuration which will trigger the rolling restart of Splunk pods for Ingestor Cluster. 
+
+We are under the investigation on how to make it fully automated. What is more, ideally, update of annotations and labels should not trigger pod restart at all and we are investigating on how to fix this behaviour eventually.
+
 # Example
 
 1. Install CRDs and Splunk Operator for Kubernetes.