zabbix-server: add extraConfig option

add types to options

nixos/modules/services/monitoring/zabbix-server.nix

@@ -32,6 +32,8 @@ let
       ${optionalString (cfg.dbPassword != "") ''
         DBPassword = ${cfg.dbPassword}
       ''}
+
+      ${config.services.zabbixServer.extraConfig}
     '';
 
   useLocalPostgres = cfg.dbServer == "localhost" || cfg.dbServer == "";
@@ -46,6 +48,7 @@ in
 
     services.zabbixServer.enable = mkOption {
       default = false;
+      type = types.bool;
       description = ''
         Whether to run the Zabbix server on this machine.
       '';
@@ -53,6 +56,7 @@ in
 
     services.zabbixServer.dbServer = mkOption {
       default = "localhost";
+      type = types.str;
       description = ''
         Hostname or IP address of the database server.
         Use an empty string ("") to use peer authentication.
@@ -61,9 +65,18 @@ in
 
     services.zabbixServer.dbPassword = mkOption {
       default = "";
+      type = types.str;
       description = "Password used to connect to the database server.";
     };
 
+    services.zabbixServer.extraConfig = mkOption {
+      default = "";
+      type = types.lines;
+      description = ''
+        Configuration that is injected verbatim into the configuration file.
+      '';
+    };
+
   };
 
   ###### implementation