[docs] update link to scoundrel in README

Author: okay

README.md

@@ -87,7 +87,7 @@ Wordlet is a clone of the popular [wordle](https://www.powerlanguage.co.uk/wordl
 ### [dumbskull](src/dumbskull)
 
 Dumbskull is a port of the games [donsol](https://100r.co/site/donsol.html) and
-[scoundrel](stfj.net/index2.php?project=art/2011/Scoundrel.pdf). It's a dungeon
+[scoundrel](https://stfj.net/index2.php?project=art/2011/Scoundrel.pdf). It's a dungeon
 crawl themed solitaire that uses a standard playing card deck.
 
 ## Demos