release-notes: mention cinnamon

Author: mkg20001

nixos/doc/manual/release-notes/rl-2009.xml

@@ -26,6 +26,12 @@
    <listitem>
     <para>GNOME desktop environment was upgraded to 3.36, see its <link xlink:href="https://help.gnome.org/misc/release-notes/3.36/">release notes</link>.</para>
    </listitem>
+   <listitem>
+     <para>
+     The Cinnamon desktop environment (v4.6) has been added. <varname>services.xserver.desktopManager.cinnamon.enable = true;</varname> to try it out!
+     Remember that, with any new feature it's possible you could run into issues, so please send all support requests to <link xlink:href="https://github.com/NixOS/nixpkgs/issues">github.com/NixOS/nixpkgs</link> to notify the maintainers.
+     </para>
+   </listitem>
    <listitem>
     <para>
     <package>maxx</package> package removed along with <varname>services.xserver.desktopManager.maxx</varname> module.