cm4-k8s-node: Add group

The Raspberry Pi CM4 nodes on the DeskPi Super 6c cluster board are
members of the _cm4-k8s-node_ group.  This group is a child of
_k8s-node_ which overrides the data volume configuration and node
labels.

group_vars/cm4-k8s-node.yml

@@ -0,0 +1,19 @@
+logical_volumes:
+  kubernetes:
+    pvs:
+    - /dev/nvme0n1
+    lvs:
+    - name: containers
+      size: 64G
+    - name: kubelet
+      size: 32G
+
+data_volumes:
+- dev: /dev/kubernetes/containers
+  fstype: ext4
+  mountpoint: /var/lib/containers
+- dev: /dev/kubernetes/kubelet
+  fstype: ext4
+  mountpoint: /var/lib/kubelet
+
+k8s_node_labels: {}