support per-release flags

Add an optional flags sub-element to the release, with "forced" being
the only defined flag for now.

Set the forced flag for the searchlight deliverables for rocky.

Change-Id: I9e0038f2dfd72c8ada2827289c538d85441b1cbe
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

README.rst

@@ -494,6 +494,13 @@ Each ``release`` entry is a mapping with keys:
   announcing the release. (Use ``|`` to indicate a multi-line,
   pre-formatted message.)
 
+``flags``
+  A list of flags attached to the release.
+
+  ``forced``
+    This release was applied by the release team, and not the project
+    team.
+
 Each entry in the ``projects`` list is a mapping with keys:
 
 ``repo``

deliverables/rocky/searchlight-ui.yaml

@@ -10,3 +10,5 @@ releases:
       - hash: 5d9ff2addf52c6ae3a76d95d781c8cc3f8e73a6b
         repo: openstack/searchlight-ui
     version: 5.0.0.0b2
+    flags:
+      - forced

deliverables/rocky/searchlight.yaml

@@ -10,3 +10,5 @@ releases:
       - hash: 17275fe95d93a5bff996c58f8de045a87fc56be5
         repo: openstack/searchlight
     version: 5.0.0.0b2
+    flags:
+      - forced

openstack_releases/schema.yaml

@@ -82,6 +82,11 @@ properties:
             additionalProperties: False
         diff-start:
           type: "string"
+        flags:
+          type: "array"
+          items:
+            type: "string"
+            enum: [ "forced" ]
       required: ["version", "projects"]
       additionalProperties: False
   branches: