Use set_toolbar_box() in example code.
Use set_toolbar_box() in example code.

The set_toolbox() method is obsolete, so let's not advertise it.

Signed-off-by: Bernie Innocenti <853520c0eaeb91fa22b7d2c2bb860b746e447d45@codewiz.org>

i5o/sugar-toolkit-gtk3,i5o/sugar-toolkit-gtk3,manuq/sugar-toolkit-gtk3,ceibal-tatu/sugar-toolkit,samdroid-apps/sugar-toolkit-gtk3,ceibal-tatu/sugar-toolkit,samdroid-apps/sugar-toolkit-gtk3,samdroid-apps/sugar-toolkit-gtk3,godiard/sugar-toolkit-gtk3,i5o/sugar-toolkit-gtk3,tchx84/debian-pkg-sugar-toolkit-gtk3,quozl/sugar-toolkit-gtk3,tchx84/sugar-toolkit-gtk3,godiard/sugar-toolkit-gtk3,quozl/sugar-toolkit-gtk3,puneetgkaur/sugar-toolkit-gtk3,manuq/sugar-toolkit-gtk3,ceibal-tatu/sugar-toolkit,quozl/sugar-toolkit-gtk3,sugarlabs/sugar-toolkit-gtk3,manuq/sugar-toolkit-gtk3,gusDuarte/sugar-toolkit-gtk3,ceibal-tatu/sugar-toolkit-gtk3,sugarlabs/sugar-toolkit,tchx84/sugar-toolkit-gtk3,i5o/sugar-toolkit-gtk3,tchx84/debian-pkg-sugar-toolkit,Daksh/sugar-toolkit-gtk3,puneetgkaur/sugar-toolkit-gtk3,godiard/sugar-toolkit-gtk3,gusDuarte/sugar-toolkit-gtk3,ceibal-tatu/sugar-toolkit-gtk3,sugarlabs/sugar-toolkit-gtk3,puneetgkaur/backup_sugar_sugartoolkit,tchx84/debian-pkg-sugar-toolkit-gtk3,tchx84/debian-pkg-sugar-toolkit,sugarlabs/sugar-toolkit,ceibal-tatu/sugar-toolkit-gtk3,Daksh/sugar-toolkit-gtk3,samdroid-apps/sugar-toolkit-gtk3,puneetgkaur/backup_sugar_sugartoolkit,sugarlabs/sugar-toolkit,puneetgkaur/backup_sugar_sugartoolkit,tchx84/sugar-toolkit-gtk3,sugarlabs/sugar-toolkit-gtk3,tchx84/debian-pkg-sugar-toolkit,quozl/sugar-toolkit-gtk3,gusDuarte/sugar-toolkit-gtk3,gusDuarte/sugar-toolkit-gtk3,sugarlabs/sugar-toolkit,Daksh/sugar-toolkit-gtk3,tchx84/debian-pkg-sugar-toolkit-gtk3,puneetgkaur/sugar-toolkit-gtk3