[release-notes] Add section on GNOME OS

[Michael Catanzaro <mcatanzaro src gnome org>]

commit e972af4d069718038fa439a55b1ac02f3f8a2a16
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Thu Sep 3 11:11:49 2020 -0500

    Add section on GNOME OS
    
    We can remove this later if we decide not to feature it here.

 help/C/developers.page | 9 +++++++++
 1 file changed, 9 insertions(+)
---
diff --git a/help/C/developers.page b/help/C/developers.page
index 8f8daa08..699c083b 100644
--- a/help/C/developers.page
+++ b/help/C/developers.page
@@ -40,6 +40,15 @@
     changing advanced settings that are not available in the user interface.</p>
   </section>
 
+  <section>
+    <title>GNOME OS</title>
+    <p>GNOME OS is a virtual machine image designed to facilitate development
+    and testing of GNOME. It is not intended to replace traditional Linux
+    distributions. Due to recent changes in Boxes’s support for UEFI, you must
+    use Boxes 3.38 to run GNOME OS images. Older versions of Boxes will not
+    work. XXX need a link.</p>
+  </section>
+
   <section>
     <title>libhandy</title>
     <p>libhandy is a library providing high-quality GTK widgets with a