[gnome-initial-setup/wip/wjt/update-contributing: 3/3] CONTRIBUTING: Document FreeIPA demo server

[Will Thompson <wjt src gnome org>]

commit 880936c5fef7cf8c57f15070038391a1ae50a8ea
Author: Will Thompson <wjt endlessos org>
Date:   Fri Sep 23 10:15:04 2022 +0100

    CONTRIBUTING: Document FreeIPA demo server

 CONTRIBUTING.md | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
---
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index bd3754d5..9c40d4ce 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -72,3 +72,17 @@ prompt, so `gnome-initial-setup` silently writes the stamp file and exits.
 
 [xdg autostart]: https://specifications.freedesktop.org/autostart-spec/autostart-spec-latest.html
     "The Desktop Application Autostart Specification"
+
+Tips for development
+====================
+
+Enterprise Login
+----------------
+
+Initial Setup can configure the system to be part of an enterprise domain.
+This functionality is available if `realmd` is installed (or, more precisely,
+the name `org.freedesktop.realmd` is owned on the system bus) and hidden if not.
+
+The FreeIPA project runs a [demo server](https://www.freeipa.org/page/Demo),
+which may be useful to test this functionality if you do not have an
+enterprise domain of your own to test against.