Dead links in 5.4 to 6.0 update guide

Created by: adrien59cadri

In this ducument: https://github.com/gitlabhq/gitlabhq/blob/master/doc/update/5.4-to-6.0.md These links are dead:

Note: We switched from Puma in GitLab 5.4 to unicorn in GitLab 6.0.

Make /home/git/gitlab/config/gitlab.yml the same as https://gitlab.com/gitlab-org/gitlab-ce/blob/masterconfig/gitlab.yml.example but with your settings. Make /home/git/gitlab/config/unicorn.rb the same as https://gitlab.com/gitlab-org/gitlab-ce/blob/masterconfig/unicorn.rb.example but with your settings.