11 chain saw manuals added

11 chain saw manuals, chain saw parts lists, and other documents were added to the site recently:

- Echo: 2 chain saw parts catalogs
- Husqvarna: 1 chain saw parts list
- McCulloch: 1 chain saw manual, 2 chain saw parts lists
- Stanley: 2 chain saw manuals, 1 chain saw service manual, 1 chain saw parts update
- Stihl: 1 chain saw technical bulletin