Update release document

Signed-off-by: Derek McGowan <derek@mcg.dev>

Author: dmcgowan

RELEASES.md

@@ -141,7 +141,8 @@ to all committers.
 | [2.0](https://github.com/containerd/containerd/releases/tag/v2.0.7)  | LTS            | November 5, 2024               | March, 2027**                  | [@samuelkarp](https://github.com/samuelkarp), [@chrishenzie](https://github.com/chrishenzie) |
 | [2.1](https://github.com/containerd/containerd/releases/tag/v2.1.0)  | Active         | May 7, 2025                    | May 5, 2026                    | @containerd/committers |
 | [2.2](https://github.com/containerd/containerd/releases/tag/v2.2.0)  | Active         | November 5, 2025               | November 6, 2026               | @containerd/committers |
-| [2.3](https://github.com/containerd/containerd/milestone/50)         | RC (LTS)       | April 29, 2026 (_scheduled_)   | April 29, 2028 (_tentative_)   | @containerd/committers |
+| [2.3](https://github.com/containerd/containerd/releases/tag/v2.3.0)  | LTS            | April 30, 2026                 | April 30, 2028                 | @containerd/committers |
+| [2.4](https://github.com/containerd/containerd/milestone/51)         | _Future_       | August 26, 2026 (_tentative_)  | April 26, 2027 (_tentative_)   | @containerd/committers |
 
 \* Support for the 1.7 release branch was provided by @containerd/committers until March 10, 2026. Extended support through September 2026 is provided by [@samuelkarp](https://github.com/samuelkarp) and [@chrishenzie](https://github.com/chrishenzie).  This extended support is focused on usage with Kubernetes 1.32, 1.31, and 1.30 via [Google Kubernetes Engine](https://cloud.google.com/kubernetes-engine).  Changes may not be accepted if they are not needed for this usage.
 
@@ -357,7 +358,8 @@ releases for prior API versions should be avoided if possible.
 | v2.0               | 1.8                    |
 | v2.1               | 1.9                    |
 | v2.2               | 1.10                   |
-| _v2.3_             | _1.11_                 |
+| v2.3               | 1.11                   |
+| _v2.4_             | _1.12_                 |
 
 
 ### Metrics API