Add Flamingo prelude section

Shamelessly copied from the cycle highlights

Signed-off-by: René Ribaud <rribaud@redhat.com>
Change-Id: Ib9de63fe4ccce24921326ef3bcfc690fd4481687

releasenotes/notes/flamingo-prelude-22a2782315ce0808.yaml

@@ -0,0 +1,52 @@
+---
+prelude: |
+  The OpenStack 2025.2 (Nova 32.0.0) release includes many new features and
+  bug fixes. Please be sure to read the upgrade section which describes the
+  required actions to upgrade your cloud from 31.0.0 (2025.1) to 32.0.0
+  (2025.2).
+  As a reminder, OpenStack 2025.2 is not a
+  `Skip-Level-Upgrade Release <https://governance.openstack.org/tc/resolutions/20220210-release-cadence-adjustment.html>`_
+  (starting from now, we name it a `SLURP release`) meaning that you can't
+  do rolling-upgrade from 2024.2, you first need to upgrade to 2025.1.
+
+  There are a few major changes worth mentioning. This is not an exhaustive
+  list:
+
+  - The latest Compute API microversion supported for 2025.2 is
+    `v2.100 <https://docs.openstack.org/nova/latest/reference/api-microversion-history.html#maximum-in-2025-1-epoxy-and-2025-2-flamingo>`_.
+
+  - The libvirt guest XML now includes additional flavor and image metadata
+    fields so that it can be used during troubleshooting or services like
+    Ceilometer can retrieve accurate instance information directly, without
+    performing extra Nova API calls.
+
+  - Nova now supports a new default role ``manager`` which is scoped to the
+    project level. This role is part of the standard role hierarchy supported
+    by Keystone and allows trusted project users to perform project-level
+    management tasks (e.g., live migration) without requiring full admin
+    rights.
+
+  - Service-to-service APIs now use the ``service`` role, reducing unnecessary
+    privileges for cross-service communication.
+
+  - Nova now supports one-time use passthrough devices. Such devices are
+    allocated to a single instance, and when the instance is deleted,
+    the device stays in a reserved state instead of becoming automatically
+    available. This ensures operators can perform necessary security checks
+    or hardware resets before reusing the device.
+
+  - Completes SPICE direct consoles with USB controller config and sound device support.
+
+  - Nova now supports QEMU’s memory balloon autodeflate and free page reporting
+    features with the libvirt driver. These allow unused guest memory to be
+    automatically released back to the hypervisor, improving memory efficiency
+    and reducing the risk of the Out-of-Memory killer activating.
+
+  - Added support for AMD Secure Encrypted Virtualization – Encrypted State
+    (SEV-ES) with libvirt, extending confidential computing capabilities in
+    Nova to protect guest memory and CPU register state.
+
+  - Experimental feature: Nova API, metadata, and scheduler services can
+    run in native threading mode as an alternative to eventlet. Please try
+    it in non-production environment and share your success or failure with
+    us on the openstack-discuss mailing list or via the Nova bug tracker.