[gnome-boxes/osinfo-from-server] recommended-downloads: Update instructions and override example

[Felipe Borges <felipeborges src gnome org>]

commit e74766113ddddb3716d44b120be3e6f817f0cc74
Author: Felipe Borges <felipeborges gnome org>
Date:   Thu Aug 4 11:01:59 2022 +0200

    recommended-downloads: Update instructions and override example
    
    This should explain to distributors how they can go about overriding
    the recommended downloads and also override "title", "subtitle" and
    "url" of a listing.
    
    This is particularly useful when you want to promote a newly released
    version of an operating system and that hasn't been shipped in an
    osinfo-db release to your users yet.

 data/recommended-downloads.xml | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)
---
diff --git a/data/recommended-downloads.xml b/data/recommended-downloads.xml
index 51b885fe..c9bd0f14 100644
--- a/data/recommended-downloads.xml
+++ b/data/recommended-downloads.xml
@@ -1,12 +1,21 @@
 <?xml version="1.0" encoding="utf-8" ?>
 <!--
-  These are OSes listed in the recommended section of the "Download an OS" page.
+  These are operating systems listed in the recommended section of the
+  "Download an OS" page.
 
-  This list is powered by libosinfo, therefore the URLs are unique identifiers
-  for each OS in osinfo-db.
+  This list is powered by libosinfo, therefore the IDs are unique identifiers
+  for each OS in osinfo-db. Use "osinfo-query os" in the CLI to list all available
+  operating systems and their respective IDs.
 
   Downstreams are encouraged to tweak the list as they wish. Sorting is also
   available.
+
+  "title", "subtitle" and "url" can be overwritten by distributors.
+
+  Distributors can host their own recommended-downloads.xml file, and point to it
+  with the org.gnome.boxes recommended-downloads-url gsetting.
+
+  See https://gitlab.gnome.org/GNOME/gnome-boxes/-/wikis/recommended-downloads.xml
  -->
 <list>
   <os id="http://redhat.com/rhel/"/>
@@ -18,5 +27,9 @@
   <os id="http://opensuse.org/opensuse/tumbleweed/"/>
   <os id="http://debian.org/debian/"/>
   <os id="http://endlessos.com/eos/"/>
-  <os id="http://gnome.org/gnome/nightly"/>
+  <os id="http://gnome.org/gnome/nightly";>
+    <title>GNOME OS Nightly</title>
+    <subtitle>The GNOME Project</subtitle>
+    <url>https://os.gnome.org/download/latest/gnome_os_installer.iso</url>
+  </os>
 </list>