adjust docs for feature maturity (#39791)

as per the [docs](https://github.com/kubernetes/website/blob/main/content/en/docs/concepts/services-networking/service.md?plain=1#L697) this is no longer an alpha feature, but stable.

Either that or I don't understand it well as a k8s noobie and it should be clarified 😄

Author: EliSzBr

content/en/docs/concepts/services-networking/service.md

@@ -656,7 +656,7 @@ by making the changes that are equivalent to you requesting a Service of
 `type: NodePort`. The cloud-controller-manager component then configures the external load balancer to
 forward traffic to that assigned node port.
 
-_As an alpha feature_, you can configure a load balanced Service to
+You can configure a load balanced Service to
 [omit](#load-balancer-nodeport-allocation) assigning a node port, provided that the
 cloud provider implementation supports this.