Update support.md (nginxinc#2693)

Adding an explicit line about dedicated support

site/content/support.md

@@ -14,3 +14,5 @@ NGINX Gateway Fabric adheres to the support policy detailed in the following kno
 - If you have any suggestions or enhancement requests, please [open an idea](https://github.com/nginxinc/nginx-gateway-fabric/discussions/categories/ideas) on GitHub discussions.
 
 - You can contact us directly, by sending an email to [[email protected]](mailto:[email protected]) or on the [NGINX Community Slack](https://nginxcommunity.slack.com/channels/nginx-gateway-fabric), in the #nginx-gateway-fabric channel.
+
+- If you need dedicated support for NGINX Gateway Fabric, or you would like to leverage our [advanced NGINX Plus features](https://docs.nginx.com/nginx-gateway-fabric/overview/nginx-plus/), you can contact [F5 Sales](https://www.f5.com/content/f5-com/en_us/products/get-f5).