doc: update magnum
diff --git a/docs/coe.md b/docs/coe.md
deleted file mode 100644
index 65190af..0000000
--- a/docs/coe.md
+++ /dev/null
@@ -1,28 +0,0 @@
-# Coe
-
-Create COE k8s cluster templates.
-
-```shell
-for version in v1.23.13 v1.24.7 v1.25.3; do
- openstack coe cluster template create \
- --image $(openstack image show ubuntu-2004-${version} -c id -f value) \
- --external-network public \
- --dns-nameserver 8.8.8.8 \
- --master-lb-enabled \
- --master-flavor m1.medium \
- --flavor m1.medium \
- --network-driver calico \
- --docker-storage-driver overlay2 \
- --coe kubernetes \
- --label kube_tag=${version} \
- k8s-${version};
-done;
-```
-
-A container registry which includes all container images required for COE k8s
-clusters is installed along side with Magnum. Instead of using external container
-registries, you can use this internal one.
-
-Append `--label container_infra_prefix="${magnum_registry_host}/magnum/"` in
-cluster create command. Replace `magnum_registry_host` with
-`openstack_helm_endpoints_magnum_registry_host` ansible variable.
diff --git a/roles/magnum/README.md b/roles/magnum/README.md
index 01bffb9..31ea12f 100644
--- a/roles/magnum/README.md
+++ b/roles/magnum/README.md
@@ -1 +1,32 @@
# `magnum`
+
+## Creating cluster templates
+
+By default, Atmosphere deploys a set of images for Kubernetes. These cover a
+range of Kubernetes versions, from 1.23.13 to 1.25.3. You can create the
+cluster templates for them with the following command:
+
+```shell
+for version in v1.23.13 v1.24.7 v1.25.3; do
+ openstack coe cluster template create \
+ --image $(openstack image show ubuntu-2004-${version} -c id -f value) \
+ --external-network public \
+ --dns-nameserver 8.8.8.8 \
+ --master-lb-enabled \
+ --master-flavor m1.medium \
+ --flavor m1.medium \
+ --network-driver calico \
+ --docker-storage-driver overlay2 \
+ --coe kubernetes \
+ --label kube_tag=${version} \
+ --label boot_volume_size=40 \
+ --label container_infra_prefix=$(kubectl -n openstack get ingress/container-infra-registry -ojsonpath='{.spec.rules[0].host}') \
+ k8s-${version};
+done;
+```
+
+> **Note**
+>
+> This command will configure the clusters to use the internal container registry
+> hosted by Atmosphere to avoid the need to talk to external registries. If you
+> want to use an external registry, you can remove the `--label container_infra_prefix`.