Removed references to private registry (#269)

Removed outdated references to private docker registry

Author: fabriziofiorucci

content/nim/deploy/kubernetes/deploy-using-helm.md

@@ -133,7 +133,6 @@ The `values.yaml` file customizes the Helm chart installation without modifying
 
     - In the `imagePullSecrets` section, add the credentials for your private Docker registry.
     - Change the version tag to the version of NGINX Instance Manager you would like to install. See "Install the chart" below for versions.
-    - Replace `<my-docker-registry:port>` with your private Docker registry and port (if applicable).
     - If deploying on OpenShift, add the `openshift.enabled: true` setting.
 
     {{< see-also >}} For details on creating a secret, see Kubernetes [Pull an Image from a Private Registry](https://kubernetes.io/docs/tasks/configure-pod-container/pull-image-private-registry/). {{</ see-also >}}
@@ -344,7 +343,6 @@ The `values.yaml` file customizes the Helm chart installation without modifying
 
     - In the `imagePullSecrets` section, add the credentials for your private Docker registry.
     - Change the version tag to the version of NGINX Instance Manager you would like to install. See "Install the chart" below for versions.
-    - Replace `<my-docker-registry:port>` with your private Docker registry and port (if applicable).
 
     {{< see-also >}} For details on creating a secret, see Kubernetes [Pull an Image from a Private Registry](https://kubernetes.io/docs/tasks/configure-pod-container/pull-image-private-registry/). {{</ see-also >}}