Document PostgreSQL primary on music and replica on master

k8s-ng/core/postgresql/cluster.yaml

@@ -3,7 +3,7 @@
 # different regions), so a failover can lose the last few transactions.
 #
 # Layout: the primary runs on the music node (the powerful one), the replica on
-# ams-1 (Europe). A failover swaps the roles; switch back with
+# master. A failover swaps the roles; switch back with
 #   kubectl cnpg promote main <instance on music>
 #
 # Nodes eligible for instances carry the label workload/postgres=true. To move a