12 mower manuals added

Links to 12 lawn mower manuals and parts lists were added to the site recently, for the following brands:

- Cub Cadet: 3 mower manuals, 1 manual supplement (& 1 broken link updated)

- MacAllister: 1 mower manual, 1 mower parts list

- McLane: 6 mower manuals (& 2 broken links updated)