Mention semantic_text going GA in serverless changelog (#2996)

Author: leemthompo

docs/en/install-upgrade/serverless-changelog.asciidoc

@@ -28,6 +28,7 @@ For serverless changes in Cloud Console, refer to https://www.elastic.co/guide/e
 * Includes spaceID in SLI documents ({kibana-pull}214278[#214278]).
 * Adds support for the MV_EXPAND command with the ES|QL rule type ({kibana-pull}212675[#212675]).
 * Enables endpoint actions for events ({kibana-pull}206857[#206857]).
+* The {ref}/semantic-text.html[`semantic_text`] field type is now GA on {{serverless-full}}.
 
 [discrete]
 [[fixes-03172025]]
@@ -578,4 +579,4 @@ For serverless changes in Cloud Console, refer to https://www.elastic.co/guide/e
 * Initializes saved objects when the **Trained Model** page loads ({kibana-pull}201426[#201426]).
 * Fixes the display of deployment stats for unallocated deployments of {ml} models ({kibana-pull}202005[#202005]).
 * Enables the solution type search for instant deployments ({kibana-pull}201688[#201688]).
-* Improves the consistency of alert counts across different views ({kibana-pull}202188[#202188]).
+* Improves the consistency of alert counts across different views ({kibana-pull}202188[#202188]).