<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Backend:etc/menu.xsd">
<menu>
<add id="VendorName_ModuleName::city" title="City List" module="VendorName_ModuleName" sortOrder="98" resource="VendorName_ModuleName::city"/>
<add id="VendorName_ModuleName::city_city" title="City" module="VendorName_ModuleName" sortOrder="99" action="route_name/controller_folder/action_name" resource="VendorName_ModuleName::city" parent="VendorName_ModuleName::city"/>
<add id="VendorName_ModuleName::city_town" title="Town" module="VendorName_ModuleName" sortOrder="100" parent="VendorName_ModuleName::city" action="route_name/controller_folder/action_name" resource="VendorName_ModuleName::city"/>
</menu>
</config>
id - id attribute is a unique identifier and will be like this format {VendorName_ModuleName}::{menu_title}.
title - this attribute is the text which will display as a menu.
module - this attribute is defined the module.
sortOrder - this attribute is defined the position of the menu. Lower value will display on top of menu.
parent - this attribute is an id of other menu. It shows that this menu is a child of another menu.
action - this attribute will shows the menu link to this format {router_name}/{controller_folder}/{action_name}.
resource - this attribute is used to defined the ACL rule. and it is useful to see menu for selected admin user which have access of this.