Menus contain pointers to subordinate nodes.1 In Info, you use menus to go to such nodes. Menus have no effect in printed manuals and do not appear in them.
By convention, a menu is put at the end of a node since a reader who uses the menu may not see text that follows it. Furthermore, a node that has a menu should not contain much text. If you have a lot of text and a menu, move most of the text into a new subnode--all but a few lines. Otherwise, a reader with a terminal that displays only a few lines may miss the menu and its associated text. As a practical matter, you should locate a menu within 20 lines of the beginning of the node.