docs: Add changelog entry for JSON_EXTRACT dynamic path arguments (#19045)

Co-authored-by: promptless[bot] <179508745+promptless[bot]@users.noreply.github.com>

Author: promptless[bot]

changelog/24.0/24.0.0/summary.md

@@ -9,6 +9,8 @@
 - **[Minor Changes](#minor-changes)**
     - **[VTGate](#minor-changes-vtgate)**
         - [New default for `--legacy-replication-lag-algorithm` flag](#vtgate-new-default-legacy-replication-lag-algorithm)
+    - **[Query Serving](#minor-changes-query-serving)**
+        - [JSON_EXTRACT now supports dynamic path arguments](#query-serving-json-extract-dynamic-args)
     - **[VTTablet](#minor-changes-vttablet)**
         - [New Experimental flag `--init-tablet-type-lookup`](#vttablet-init-tablet-type-lookup)
         - [Tablet Shutdown Tracking and Connection Validation](#vttablet-tablet-shutdown-validation)
@@ -40,6 +42,16 @@ Instead, a simpler algorithm purely based on low lag, high lag and minimum numbe
 
 In v25 this flag will become deprecated and in the following release it will be removed. In the meantime, the legacy behaviour can be used by setting `--legacy-replication-lag-algorithm=true`. This deprecation is tracked in https://github.com/vitessio/vitess/issues/18914.
 
+### <a id="minor-changes-query-serving"/>Query Serving</a>
+
+#### <a id="query-serving-json-extract-dynamic-args"/>JSON_EXTRACT now supports dynamic path arguments</a>
+
+The `JSON_EXTRACT` function now supports dynamic path arguments like bind variables or results from other function calls. Previously, `JSON_EXTRACT` only worked with static string literals for path arguments.
+
+Null handling now matches MySQL behavior. The function returns NULL when either the document or path argument is NULL.
+
+Static path arguments are still optimized, even when mixed with dynamic arguments, so existing queries won't see any performance regression.
+
 ### <a id="minor-changes-vttablet"/>VTTablet</a>
 
 #### <a id="vttablet-init-tablet-type-lookup"/>New Experimental flag `--init-tablet-type-lookup`</a>