adding reference to supported K8s versions and juju versions

Author: deusebio

docs/reference/requirements.md

@@ -15,3 +15,27 @@ The following are the minimum system requirements for Charmed Apache Spark:
   [Canonical Apache Spark image](https://github.com/canonical/charmed-spark-rock/pkgs/container/charmed-spark).
 - Access to a Kubernetes cluster, e.g. [MicroK8s](https://microk8s.io/) or
   [Charmed Kubernetes](https://ubuntu.com/kubernetes/charmed-k8s).
+
+## Recommended versions
+
+### Kubernetes
+
+We recommend deploying Charmed Spark on top of a Canonical Kubernetes cluster at version 1.32 LTS.
+
+Charmed Spark has also been validated on various Kubernetes versions (1.28, 1.29, 1.30, 1.31, 1.33 and 1.34) on AMD/CPU nodes.
+GPU and ARM support have been validated for Kubernetes versions 1.32, 1.33 and 1.34.
+
+Charmed Spark has also been validated on other Kubernetes distributions among which:
+* MicroK8s (from version 1.28 to version 1.34) on AMD/CPU nodes
+* Azure AKS (on version 1.32)
+* Amazon EKS (on version 1.27)
+
+### Juju 
+
+We recommend deploying Charmed Spark on top of Juju 3.6.9.  
+
+```{note}
+Juju controller versions from 3.9.10 to 3.6.13 are affected by a [regression in Juju](https://github.com/juju/juju/issues/21312) that has been fixed in 3.6.14.
+Support for Juju 3.6.14+ is currently being addressed by [this issue](https://github.com/canonical/spark-integration-hub-k8s-operator/issues/119). 
+```
+