fix typo 'for'

Author: githubteacher

README.md

@@ -12,7 +12,7 @@ Bit.ly link for mobile:
 http://bit.ly/html5-invasion
 
 
-If you make an interesting for fork or enhancement of the game, let me know and it'll get
+If you make an interesting fork or enhancement of the game, let me know and it'll get
 linked to here. This original repo will stay matching the code in the book.
 
 For more  [HTML5 Game Development](http://www.html5gamedevelopment.org) resources, see: