Merge branch 'kerberos-docs' into 'master'

Remove incorrect settings

These settings do not work, in fact they prevent GitLab from booting.
They are also not needed because Kerberos integration uses
/etc/krb5.conf on the GitLab server.

See merge request !514

doc/integration/kerberos.md

@@ -7,12 +7,7 @@ Kerberos integration can be enabled as a regular omniauth provider, edit [gitlab
 gitlab_rails['omniauth_enabled'] = true
 gitlab_rails['omniauth_allow_single_sign_on'] = ['kerberos']
 gitlab_rails['omniauth_providers'] = [
-    {
-        "name" => "kerberos",
-        "app_id" => "YOUR APP ID",
-        "app_secret" => "YOUR APP SECRET",
-        "args" => { "access_type" => "offline", "approval_prompt" => "" }
-    }
+    {"name" => "kerberos"}
 ]
 ```