Apply suggestions from code review

Author: lena-larionova

app/_hub/kong-inc/datadog/_changelog.md

@@ -1,6 +1,6 @@
 ## Changelog
 
-### {{site.base_gateway}} 3.8.x
+### {{site.base_gateway}} 3.9.x
 * Added route name to metrics, and allowed the `route-name` tag to be customized through the configuration parameter `route_name_tag`.
  [#13494](https://github.com/Kong/kong/pull/13494)