Menus contain pointers to subordinate nodes. In Info output, you use menus to go to such nodes. Menus can be used in HTML output but are not used in the default case. Menus have no effect in printed manuals and do not appear in them. Menus are ignored in DocBook output.
Menus are automatically generated by texi2any when outputting
Info for nodes followed by a sectioning command, without menu, and with
automatic pointers. In a hierarchically organized manual with sectioning
commands associated with nodes and with node pointers left out, you should
only write menus if you want to have descriptions especially formatted
in Info.