docs: add release notes for v0.9.0-alpha0

This is an alpha release, so let's be clear about exactly
what the limitations are.

Signed-off-by: Tobin Feldman-Fitzthum <tobin@ibm.com>

releases/v0.9.0-alpha0.md

@@ -0,0 +1,79 @@
+# Release Notes for v0.9.0-alpha
+
+Release Date: May 2nd, 2024
+
+This is our first release based on Kata Containers main, but it is an alpha release that supports
+only a subset of features.
+
+This release is based on [3.4.0](https://github.com/kata-containers/kata-containers/releases/tag/3.4.0) of Kata Containers
+and [v0.9.0](https://github.com/confidential-containers/enclave-cc/releases/tag/v0.9.0) of enclave-cc.
+
+This release supports pulling images inside of the guest with some caveats but it does
+not support pulling encrypted or signed images inside the guest.
+This release supports attestation and includes the guest components in the rootfs,
+but it does not support any TEE platform.
+Peer pods is also not supported.
+
+**This release was created mainly for development purposes. For a full feature set,
+consider returning to v0.8.0 or using the next release.**
+
+Please see the [quickstart guide](../quickstart.md) for details on how to try out Confidential
+Containers.
+
+Please refer to our [Acronyms](https://github.com/confidential-containers/documentation/wiki/Acronyms)
+and [Glossary](https://github.com/confidential-containers/documentation/wiki/Glossary) pages for a
+definition of the acronyms used in this document.
+
+## What's new
+
+* This release is built from the main branch of Kata Containers.
+* Non-tee attestation is now based on a sample attester and verifier rather than on `offline_fs_kbc`.
+    * Resources can be dynamically delivered in confidential environments.
+    * Trustee is integrated into the Kata Containers CI.
+* All platforms now share one confidential rootfs.
+* All platforms share one confidential guest kernel.
+* Image request timeout is configurable to facilitate pulling large images.
+* Attestation Agent now supports generic `configfs-tsm` ABI for collecting evidence.
+* Enclave-cc moves to unified LibOS bundle for secure rootfs key handling and to the latest Occlum v0.30.1 release that adds SGX EDMM support for dynamically adjusting the enclave size.
+* Adoption of a project-wide security reporting protocol
+
+## Hardware Support
+
+This release does not officially support any hardware platforms.
+It is mainly intended for testing in non-tee environments.
+Future releases will return to previous levels of support.
+
+## Limitations
+
+The following are known limitations of this release:
+
+* Nydus snapshotter support is not mature.
+  * Nydus snapshot sometimes conflicts with existing node configuration.
+  * You may need to remove existing container images/snapshots before installing Nydus snapshotter.
+  * Nydus snapshotter may not support pulling one image with multiple runtime handler annotations even across different pods.
+    * These limitations can apply to the pause image when filesystem passthrough is not enabled.
+  * Host pulling with Nydus snapshotter is not yet enabled.
+  * Nydus snapshotter is not supported with enclave-cc.
+* Pulling container images inside guest may have negative performance implications including greater resource usage and slower startup.
+* `crio` support is still evolving.
+* Platform support is rapidly changing
+* SELinux is not supported on the host and must be set to permissive if in use.
+* The format of encrypted container images is still subject to change
+  * The [oci-crypt](https://github.com/containers/ocicrypt) container image format itself may still change
+  * The tools to generate images are not in their final form
+  * The image format itself is subject to change in upcoming releases
+  * Not all image repositories support encrypted container images.
+* Complete integration with Kubernetes is still in progress.
+  * OpenShift support is not yet complete.
+  * Existing APIs do not fully support the CoCo security and threat model. [More info](https://github.com/confidential-containers/community/issues/53)
+  * Some commands accessing confidential data, such as `kubectl exec`, may either fail to work, or incorrectly expose information to the host
+* The CoCo community aspires to adopting open source security best practices, but not all practices are adopted yet.
+  * We track our status with the OpenSSF Best Practices Badge, which improved to 75% at the time of this release.
+  * Community has adopted a security reporting protocol, but application and documentation of static and dynamic analysis still needed.
+* Container metadata such as environment variables are not measured.
+* Kata Agent does not validate mount requests. A malicious host might be able to mount a shared filesystem into the PodVM.
+
+## CVE Fixes
+
+None
+