Where can I find information on developing an extension for ISPManager?

Question

ISPmanager

Panel version: ISPmanager Lite 5.128.0
went through their info wiki on plugin development, but not a single example works, given that the articles there are 6 years old, most likely something has changed in the extension mechanism.
created file /usr/local/mgr5/etc/xml/ispmgr_mod_myconf.xml

<?xml version="1.0" encoding="utf-8"?>
<mgrdata>
     <mainmenu level="admin+">
         <node name="tool">
             <node name="node1" type="list" />
         </node>
     </mainmenu>
     <metadata name="node1" type="list" key="item">
          <coldata>
            <col sort="alpha" sorted="yes" name="item" type="data"/>
          </coldata>
     </metadata>
     <lang name="en">
          <messages name="desktop">
            <msg name="menu_node1">Test module</msg>
          </messages>                                                                                                                                                                
    </lang>
    <lang name="ru">
          <messages name="desktop">
            <msg name="menu_node1">Тестовый модуль</msg>
          </messages>
    </lang>
</mgrdata>

crashed the cache in /usr/local/mgr5/var/.xmlcache
restarted the panel As a result, the item was not added to the sidebar. What am I doing wrong and where can I find up-to-date information on developing extensions for . ISPManager? /usr/local/mgr5/sbin/mgrctl -m ispmgr exit