diff --git a/readme.md b/readme.md
index b0242b5..c95e3d5 100644
--- a/readme.md
+++ b/readme.md
@@ -5,3 +5,5 @@ Push your SSH keys to all machines to the `administrator` user. Here is a sample
 ```
 ansible-playbook -i hosts -l PoM --key-file ~/.ssh/keys/gjk-ansible -K update.yaml
 ```
+
+GDM configuration can be found at <https://help.gnome.org/admin/system-admin-guide/stable/index.html.en>.