Proxy documentation should give port other than 8080 as example

https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/doc/settings/nginx.md#setting-the-nginx-listen-port Because 8080 is used by unicorn apparently. Errors from unicorn about port 8080 already in use when I started gitlab, latest omnibus package on debian 8 as of today. Switching 8081 seems to work.