quickstart: Add a note on prequisites about SELinux

The operator does not work(**) with SELinux enabled and enforced. Added
a note about it on the prequisites section.

(**) confidential-containers/operator#115

Signed-off-by: Wainer dos Santos Moschetta <wainersm@redhat.com>

quickstart.md

@@ -46,7 +46,7 @@ on the worker nodes is **not** on an overlayfs mount but the path is a `hostPath
 - Only containerd runtime based Kubernetes clusters are supported with the current CoCo release
 - The minimum Kubernetes version should be 1.24
 - Ensure at least one Kubernetes node in the cluster is having the label `node-role.kubernetes.io/worker=`
-
+- Ensure SELinux is disabled or not enforced (https://github.com/confidential-containers/operator/issues/115)
 
 For more details on the operator, including the custom resources managed by the operator, refer to the operator [docs](https://github.com/confidential-containers/operator).