[DOCS] Remove technical preview from Serverless API intro

Author: lcawl

docs/overlays/elasticsearch-serverless-openapi-overlays.yaml

@@ -9,10 +9,6 @@ actions:
     update:
       title: Elasticsearch Serverless API
       description: >
-        **Technical preview**  
-        This functionality is in technical preview and may be changed or removed in a future release.
-        Elastic will work to fix any issues, but features in technical preview are not subject to the support SLA of official GA features.
-
         ## Documentation source and versions
         
         This documentation is derived from the `main` branch of the [elasticsearch-specification](https://github.com/elastic/elasticsearch-specification) repository.