Update retired project stable branch handling

When any project/repo is retired, we used to mark its
delivreables in stable branches as 'retired' so that release
team can use that flag to indentifiy the retired project.

Retirement means no maintenance for master as well as for
stable branches so it make sense to directly EOL all the
supported stable branches during retirement process.

Change-Id: Id6229dab375322b1026ffc8bbbb85058166f33a7

doc/source/repository.rst

@@ -146,8 +146,8 @@ will redirect to the repositories' ``README.rst`` file.
 
 NOTE: use Depends-On on ``governance`` patch submitted in Step 3.
 
-Step 8: Mark the deliverables as retired
-----------------------------------------
+Step 8: EOL all stable branches
+-------------------------------
 
 Given that this project is being retired, there will be no more releases.
 Thus you must do two tasks in the ``openstack/releases`` repository.
@@ -157,33 +157,29 @@ corresponding to the current development cycle.  For example, if your
 deliverable is ``puppet-panko`` and the current development cycle is
 Ussuri, you must delete ``deliverables/ussuri/puppet-panko.yaml``.
 
-Next, if your deliverable has stable branches, for example, ``stable/train``,
-you must amend the related deliverable files to tag the project with the
-``retired`` flag.  (We don't delete these yaml files because they contain
-important historical information about the releases that have previously
-occurred on these branches.)
+Next, if your deliverable has supported stable branches, for example,
+``stable/train``, you must EOL it with the latest released hash of
+that stable branch (not the latest hash exists on that stable branch,
+which means no new release even though there were some unreleased
+backports).
 
 Example with ``deliverables/train/puppet-panko.yaml``::
 
     ---
-    launchpad: puppet-panko
-    release-model: cycle-trailing
-    team: Puppet OpenStack
-    type: other
-    repository-settings:
-      openstack/puppet-panko:
-        flags:
-          - retired
+  - version: train-eol
+    projects:
+      - repo: openstack/puppet-panko
+        hash: da522675438c3edf31998558938ecca0c7895bb5
     ...
 
-Even if a project is retired, stable branches will continue to follow the
-existing series life cycle and this flag will allow us to ignore this
-deliverable in some specific cases.
-
+# TODO(gmann): update the below example with the changes doing EOLing
+# stable branches.
 For a complete example, here's the gerrit review that retired the
 winstacker project's deliverables during the Bobcat development cycle:
 https://review.opendev.org/c/openstack/releases/+/887238
 
+No action is needed for already EOL or unmaintained branches.
+
 NOTE: use Depends-On on ``governance`` patch submitted in Step 3.
 
 Step 9: Update openstack-map to remove the retired project