Update Sinatra Recipes hyperlink

Author: jkowens

contributing.markdown

@@ -66,10 +66,8 @@ GitHub to track patch requests.
   repository](http://github.com/sinatra/sinatra-book/) and build process but is
   managed the same as the website and project codebase.
 
-* [Sinatra Recipes](http://recipes.sinatrarb.com/) is a community
-  project where anyone is free to contribute ideas, recipes and tutorials. Which
-  also has its own [git
-  repository](http://github.com/sinatra/sinatra-recipes).
+* [Sinatra Recipes](http://github.com/sinatra/sinatra-recipes) is a community
+  project where anyone is free to contribute ideas, recipes and tutorials.
 
 * [The Introduction](intro.html) is generated from Sinatra's
   [README file](http://github.com/sinatra/sinatra/blob/master/README.md).