Updated the tutorial URL.
Updated the tutorial URL.

briantrice/slate-language,briantrice/slate-language,briantrice/slate-language,briantrice/slate-language,krfkeith/slate-language,briantrice/slate-language,krfkeith/slate-language,krfkeith/slate-language,krfkeith/slate-language,briantrice/slate-language,krfkeith/slate-language,krfkeith/slate-language