A comment for Shibboleth.md

In doc/integration/shibboleth.md (gitlab-ce@d76c5824bc05640d276be96f7853f2d266fd6750), an example using Apache mod_shib2 is introduced. I think that it is nice for Gitlab & Shibboleth users :)

In the example configuration, while 'upper case' attributes, like HTTP_EPPN, are manually appended, it may be easier to use :request_type option supported in omniauth-shibboleth 1.0.8.

gitlab_rails['omniauth_providers'] = [
  {
    "name" => 'shibboleth',
    "args" => {
      "request_type" => 'header',
      "name_field" => 'cn',
      "info_fields" => { "email" => 'mail'}
    }
  }
]

Furthermore, another option for gitlab-omnibus package (handling Shibboleth request in Nginx environment) is using rack-saml with omniauth-shibboleth. It may be more easier because it does not require Apache and mod_shib2.

I am sorry that I do not have enough time to test them. If someone is interested in them, please test and update Shibboleth.md :)

Best