Fixed grammatical error.

app/views/projects/show.html.haml

@@ -38,7 +38,7 @@
       %hr
       %p
       %p Repo Size: #{@project.repository.size} MB
-      %p Created at: #{@project.created_at.stamp('Aug 22, 2013')}
+      %p Created on: #{@project.created_at.stamp('Aug 22, 2013')}
       %p Owner: #{link_to @project.owner_name, @project.owner}
       - if @project.forked_from_project
         %p