Update series statuses

- Train and Ussuri will transition to End of Life
- The last 3 series in Extended Maintenance will transition to
  Unmaintained (Xena, Wallaby, Victoria)
- Yoga is now Unmaintained
- Zed and newer branches will transition to Unmaintained after their
  3rd subsequent series is officially released (~18 months)

This patch also:
- extends the note about the maintenance phases
- refines Zed's planned transition date to Unmaintained to a less busy
  date, ~1 month after the official 2024.1 Caracal release

Change-Id: I860f5056a5563c1e8377dfc7d4f9c31f28912e3c

data/series_status.yaml

@@ -19,7 +19,7 @@
   status: maintained
   initial-release: 2023-10-04
   next-phase:
-    status: extended maintenance
+    status: end of life
     date: 2025-04-04
 - name: antelope
   release-id: 2023.1
@@ -27,20 +27,19 @@
   slurp: yes
   initial-release: 2023-03-22
   next-phase:
-    status: extended maintenance
+    status: unmaintained
     date: 2024-09-22
 - name: zed
   status: maintained
   initial-release: 2022-10-05
   next-phase:
-    status: extended maintenance
+    status: unmaintained
-    date: 2024-04-05
+    date: 2024-05-02
 - name: yoga
-  status: maintained
+  status: unmaintained
   initial-release: 2022-03-30
   next-phase:
-    status: extended maintenance
+    status: end of life
-    date: 2023-11-02
 - name: xena
   status: extended maintenance
   initial-release: 2021-10-06
@@ -60,12 +59,12 @@
   status: extended maintenance
   initial-release: 2020-05-13
   next-phase:
-    status: unmaintained
+    status: end of life
 - name: train
   status: extended maintenance
   initial-release: 2019-10-16
   next-phase:
-    status: unmaintained
+    status: end of life
 - name: stein
   status: end of life
   initial-release: 2019-04-10

doc/source/index.rst

@@ -55,8 +55,13 @@ updates.
    releases/*
 
 .. note::
-   The schedule of `Maintenance phases`_ changed during Ocata.
+   The schedule of `Maintenance phases`_ changed during Ocata
+   and also during 2024.1 Caracal.
    The `old phases`_ were used until Newton.
+   The last series that transitioned to Extended Maintenance was Xena.
+   The replacement of Extended Maintenance process to Unmaintained
+   was formulated in the `2023-07-24 Unmaintained status replaces
+   Extended Maintenance`_ resolution.
 
 .. _extended-maintenance-note:
 
@@ -68,6 +73,7 @@ updates.
 
 .. _Maintenance phases: https://docs.openstack.org/project-team-guide/stable-branches.html#maintenance-phases
 .. _old phases: https://github.com/openstack/project-team-guide/blob/1c837bf0~/doc/source/stable-branches.rst
+.. _2023-07-24 Unmaintained status replaces Extended Maintenance: https://governance.openstack.org/tc/resolutions/20230724-unmaintained-branches.html
 
 Series-Independent Releases
 ===========================