Change suggestion copy.

README.md

@@ -588,4 +588,4 @@ Various resources, such as books, websites and articles, for improving your PHP
 
 # Suggestions
 
-Please leave any suggestions in the gist comments, or send a tweet to [@jamieyork](https://twitter.com/jamieyork).
+Please open an issue for any new suggestions or send a tweet to [@jamieyork](https://twitter.com/jamieyork).