fix: Update shoot creation How-To guide for new parameters

Two new parameters are visible while creating a new shoot
cluster. Those are related to the load balancer provider and
the availability zones. At the moment, they are both preset and
cannot be changed. Because of that, we update two screenshots
and modify the prose accordingly.

docs/howto/kubernetes/gardener/create-shoot-cluster.md

@@ -25,8 +25,9 @@ At the top right-hand side of the central pane, click on *Create Kubernetes cl
 A new pane named *Create {{k8s_management_service}} Shoot Cluster* slides over from the right-hand side of the browser.
 Type in a name for the new shoot cluster, and select a region.
 Also, select the version of Kubernetes the new cluster will be running.
-In the example below, we have chosen version 1.30.5.
-At the time of writing, that was the latest supported in {{brand}}.
+In the example below, we have chosen version 1.30.5, which, at the time of writing, was the latest supported in {{brand}}.
+Please note the *Load balancer provider* and *Availability Zone* parameters.
+Both are already set and for the time being, you cannot modify any of them.
 
 !["Create {{k8s_management_service}} Shoot Cluster" panel, showing options to type in a cluster name, select region and Kubernetes version](assets/create-shoot-01.png)