Update to plural (grammar fix)

Minor change of ingress controller -> ingress controllers for grammatical agreement with the rest of the sentence.

Author: kaihoffman

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

@@ -80,7 +80,7 @@ The name of an Ingress object must be a valid
 For general information about working with config files, see [deploying applications](/docs/tasks/run-application/run-stateless-application-deployment/), [configuring containers](/docs/tasks/configure-pod-container/configure-pod-configmap/), [managing resources](/docs/concepts/cluster-administration/manage-deployment/).
  Ingress frequently uses annotations to configure some options depending on the Ingress controller, an example of which
  is the [rewrite-target annotation](https://github.com/kubernetes/ingress-nginx/blob/master/docs/examples/rewrite/README.md).
-Different [Ingress controller](/docs/concepts/services-networking/ingress-controllers) support different annotations. Review the documentation for
+Different [Ingress controllers](/docs/concepts/services-networking/ingress-controllers) support different annotations. Review the documentation for
  your choice of Ingress controller to learn which annotations are supported.
 
 The Ingress [spec](https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status)