menudata.xml is in part maintained by this script:
  gui/wxpython/tools/update_menudata.py

which updates the description and keywords (based on module's
module->label or module->description, module->keywords), and is in
part maintained by editing the file directly.

Other items (menu structure, menu item label descriptions) are
untouched by the update_menudata.py script and should be edited
in the menudata.xml file directly.


menuitem breakdown:

<command>   The name of the executable.  e.g. "r.info".

<label>     The menu short description. [maintained in this file]

<handler>   The python function that handles the command.
	     e.g.OnMenuCmd, many others..

<help>      automatically populated by update_menudata.py from
	     the <command> module's module->description (or if
	     it exists, module->label).  [do not edit]

<keywords>  automatically populated by update_menudata.py from
	     the <command> module's module->keywords.  [do not edit]
	     (G_add_keyword() in GRASS 7+)

<icon>      optional icon to be shown in the menu