Update docs to use 4-0-stable recipes
updating rails to 3.2.11 in response to CVE-2013-0156

See also:
https://github.com/gitlabhq/gitlabhq/issues/2526
http://www.securityfocus.com/bid/57187
Merge pull request #2532 from dvanduzer/4-0-stable

updating rails to 3.2.11 in response to CVE-2013-0156