docs: Redwood release notes first cut.

source/community/release_notes/index.rst

@@ -11,7 +11,7 @@ The *Open edX Platform Release Notes* provide information about releases, migrat
 .. toctree::
     :maxdepth: 2
 
-    Redwood: The next release <redwood>
-    Quince: The current release <quince>
+    Redwood: The current release <redwood>
+    Sumac: The next release <sumac>
     named_release_branches_and_tags
     old_releases

source/community/release_notes/old_releases.rst

@@ -11,6 +11,7 @@ fixes and features. These older releases will not receive any of those.
 .. toctree::
    :maxdepth: 2
 
+   quince
    palm
    olive
    nutmeg