add to release notes about last_insert_id

Signed-off-by: Andres Taylor <andres@planetscale.com>

changelog/22.0/22.0.0/summary.md

@@ -10,6 +10,7 @@
   - **[VTOrc Config File Changes](#vtorc-config-file-changes)**
   - **[VTGate Config File Changes](#vtgate-config-file-changes)**
   - **[Support for More Efficient JSON Replication](#efficient-json-replication)**
+  - **[Support for LAST_INSERT_ID(x)](#last-insert-id)**
 - **[Minor Changes](#minor-changes)**
   - **[VTTablet Flags](#flags-vttablet)**
   - **[Topology read concurrency behaviour changes](#topo-read-concurrency-changes)**
@@ -80,6 +81,12 @@ In [#7345](https://github.com/vitessio/vitess/pull/17345) we added support for [
 
 If you are using MySQL 8.0 or later and using JSON columns, you can now enable this MySQL feature across your Vitess cluster(s) to lower the disk space needed for binary logs and improve the CPU and memory usage in both `mysqld` (standard intrashard MySQL replication) and `vttablet` ([VReplication](https://vitess.io/docs/reference/vreplication/vreplication/)) without losing any capabilities or features.
 
+### <a id="last-insert-id"/>Support for `LAST_INSERT_ID(x)`</a>
+
+In [#17408](https://github.com/vitessio/vitess/pull/17408) and [#17409](https://github.com/vitessio/vitess/pull/17409), we added the ability to use `LAST_INSERT_ID(x)` in Vitess directly at vtgate. This improvement allows certain queries—like `SELECT last_insert_id(123);` or `SELECT last_insert_id(count(*)) ...`—to be handled without relying on MySQL for the final value.
+
+**Limitations**:
+- When using `LAST_INSERT_ID(x)` in ordered queries (e.g., `SELECT last_insert_id(col) FROM table ORDER BY foo`), MySQL sets the session’s last-insert-id value according to the *last row returned*. Vitess does not guarantee the same behavior.
 
 ## <a id="minor-changes"/>Minor Changes</a>