HCP proper node selector for infra nodes

Just a few lines above, the docs say:
`node-role.kubernetes.io/infra`: Use this label to avoid having the
control-plane workload count toward your subscription

The nodeSelector should match the label.

Author: mgencur

modules/hcp-labels-taints.adoc

@@ -40,7 +40,7 @@ To enable a hosted cluster to require its pods to be scheduled into infrastructu
 ----
   spec:
     nodeSelector:
-      role.kubernetes.io/infra: ""
+      node-role.kubernetes.io/infra: ""
 ----
 
 This way, {hcp} for each hosted cluster are eligible infrastructure node workloads, and you do not need to entitle the underlying {product-title} nodes.