postgresql.yaml: update stale comment referencing old CLONE_* rationale to reference standby_cluster design (no functional change - this file never used CLONE_* itself)

postgresql/postgresql.yaml

@@ -161,9 +161,11 @@ services:
       SPILO_CONFIGURATION: |
         bootstrap:
           post_init: /scripts/post_init_wrapper.sh "zalandos"
-      # CLONE_* vars intentionally omitted here — enabled only at cutover
-      # (Phase 3) to seed from the existing 41GB single instance via
-      # pg_basebackup. See ADR-0001 note before cutover.
+      # standby_cluster is NOT configured in this steady-state bootstrap file —
+      # it only applies during Phase 3 cutover staging
+      # (postgresql/cutover/postgresql-ha-staging.yaml), which streams
+      # continuously from the live single instance until promotion. See
+      # ADR-0001 Dry-Run Debugging Log note for the standby_cluster design.
     secrets:
       - postgresql_password
       - postgresql_replication_password