Luci - add new menu into installed OpenWRT 19

Is it possible to add new menu into Luci on installed OpenWRT 19?
I have this done on ver. 15 and 18 by editing /usr/lib/lua/luci/controller/admin/index.lua, but seems on ver.19 there is different way for adding new menu.
I've read wiki:
but as far I understand - this is way for editing sources and compiling Luci with changes.
Im looking for way to change Luci on already configured router.
Please advice.