Remove link duplication from includes_chef_for_more_info.rst

Right now both opscode_community and opscode_cookbooks goes to http://community.opscode.com, this patch replaces second link with http://community.opscode.com/cookbooks.

Also there is rather misleading `|url opscode_cookbooks| replace:: http://community.opscode.com/` in swaps/swap_names.txt, maybe it should be changed to http://community.opscode.com/cookbooks instead.