Added link to online roll tool

It suddenly dawned on me that anyone who finds Freehack via itch.io will have a difficult time figuring out how to use its unique roll mechanic in practice due to its mathematical complexity. I have been using an online tool, hosted on my website, to do this for years but this was never mentioned on the itch.io page. I have now corrected this and a link can be found at the bottom of the page.

Apologies for any inconvenience caused.