update docs and change order in config

docs/reference/operator_parameters.md

@@ -161,6 +161,13 @@ configuration they are grouped under the `kubernetes` key.
   replaced by the cluster name. Only the `{cluster}` placeholders is allowed in
   the template.
 
+* **enable_pod_disruption_budget**
+  if disabled `MinAvailable` in the PDB's spec will be set to `0`. That means
+  the PDB will get created anyway. The PDB is also relaxed when scaling down the
+  Postgres cluster to `"numberOfInstances": 0`. When scaling up or enabling this
+  configuration parameter delete the operator Pod to get the PDB synced. By
+  default PDB is enabled which results in `"MinAvailable": 1`
+
 * **secret_name_template**
   a template for the name of the database user secrets generated by the
   operator. `{username}` is replaced with name of the secret, `{cluster}` with