use min instances 2 everywhere and update reference docs

charts/postgres-operator/crds/operatorconfigurations.yaml

@@ -341,7 +341,8 @@ spec:
                   #default: "transaction"
                 connection_pool_number_of_instances:
                   type: integer
-                  #default: 1
+                  minimum: 2
+                  #default: 2
                 connection_pool_default_cpu_limit:
                   type: string
                   pattern: '^(\d+m|\d+(\.\d{1,3})?)$'

charts/postgres-operator/crds/postgresqls.yaml

@@ -120,7 +120,7 @@ spec:
                     - "transaction"
                 numberOfInstances:
                   type: integer
-                  minimum: 1
+                  minimum: 2
                 resources:
                   type: object
                   required:

charts/postgres-operator/values.yaml

@@ -258,7 +258,7 @@ configConnectionPool:
   # default pooling mode
   connection_pool_mode: "transaction"
   # number of pooler instances
-  connection_pool_number_of_instances: 1
+  connection_pool_number_of_instances: 2
   # default resources
   connection_pool_default_cpu_request: "1"
   connection_pool_default_memory_request: "100Mi"