Incorrect URL links on /help page

Reported by user: http://www.twitter.com/drcongo/status/725933375987441665

Links on https://gitlab.com/help/ have an additional /helpappended to the url.

Help is propagated from https://gitlab.com/gitlab-org/gitlab-ee/blob/master/doc/README.md

http://docs.gitlab.com/ee/

//cc @axil