Gh-489: Add notice about Kubernetes limitation (#499)

Add/update Kubernetes notice

docs/administration-guide/gaffer-deployment/kubernetes-guide/helm-configuration.md

@@ -1,8 +1,9 @@
 # Configuring Gaffer with Helm
 
 !!! warning
- Configuration via Helm is under development the information here is subject
- to change in future releases.
+ Gaffer Kubernetes is not currently up to date. You will need to use a
+ version of Kubernetes <= 1.25 for deployments.
+ The information here is subject to change in future releases.
 
 The general overview of what you can configure in a Gaffer graph is outlined
 under the [configuring Gaffer pages](../../gaffer-config/config.md). However,

docs/administration-guide/gaffer-deployment/kubernetes-guide/running-on-kubernetes.md

@@ -1,5 +1,10 @@
 # Running Gaffer on Kubernetes
 
+!!! warning
+ Gaffer Kubernetes is not currently up to date. You will need to use a
+ version of Kubernetes <= 1.25 for deployments.
+ The information here is subject to change in future releases.
+
 Gaffer's Open Container Initiative (OCI) images mean it is also possible to
 deploy via kubernetes to give an alternative scalable deployment. This guide
 will assume the reader is familiar with general usage of kubernetes, further

docs/administration-guide/gaffer-deployment/kubernetes-guide/simple-deployment.md

@@ -1,5 +1,10 @@
 # Creating a Simple Deployment
 
+!!! warning
+ Gaffer Kubernetes is not currently up to date. You will need to use a
+ version of Kubernetes <= 1.25 for deployments.
+ The information here is subject to change in future releases.
+
 This guide will describe how to deploy a simple graph on a Kubernetes cluster
 with the minimum configuration. It is assumed you have read the [previous page](./running-on-kubernetes.md)
 to get an overview of running Gaffer on Kubernetes.