Update servers.adoc

Author: NataliaIvakina

modules/ROOT/pages/clustering/servers.adoc

@@ -485,6 +485,8 @@ If you want to keep both values `modeConstraint:'SECONDARY'` and `allowedDatabas
 ----
 ALTER SERVER '25a7efc7-d063-44b8-bdee-f23357f89f01' SET OPTIONS {modeConstraint:'SECONDARY', allowedDatabases:['foo']};
 ----
+
+Always check the current configuration with `SHOW SERVERS YIELD *` and reapply unchanged options when using `ALTER SERVER`.
 ====
 
 === Renaming a server