wxGUI/toolboxes: reflecting the change in https://trac.osgeo.org/grass/changeset/57000 and noting the need for valid XML file

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@57001 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/wxguitoolboxes.dox

@@ -121,9 +121,9 @@ it is used to create a menu.
 When \c toolboxes.xml or \c main_menu.xml file is not in user home directory
 but \c menudata.xml is, the file is re-generated (each time the GUI starts).
 So, if you just have your own \c main_menu.xml, it is better to create also
-a \c toolboxes.xml file with no toolboxes (you may want to remove
-\c "<user-toolboxes-list>" tag from your \c main_menu.xml file because it will
-be no longer ignored). Similarly, if you have only the \c toolboxes.xml file it
+a \c toolboxes.xml file with no toolboxes (note that you still need to create
+a valid XML toolbox file).
+Similarly, if you have only the \c toolboxes.xml file it
 is better to copy the \c main_menu.xml file from distribution into your home
 directory.