Move NAP DoS chart to new repo (#3674)

The source code of the NAP DoS Arbitrator Helm Chart was added to this repo, but the Chart can be used independently for the Ingress Controller.

This PR removes the source code from this repo and updates the documentation to point to the new location where the Helm Chart is going to live.

The new chart repo is https://github.com/nginxinc/nap-dos-arbitrator-helm-chart

Author: lucacome

deployments/helm-chart-dos-arbitrator/.helmignore

@@ -13,7 +13,7 @@ This chart deploys the NGINX Ingress Controller in your Kubernetes cluster.
     - Alternatively, pull an Ingress Controller image with NGINX Plus and push it to your private registry by following the instructions from [here](https://docs.nginx.com/nginx-ingress-controller/installation/pulling-ingress-controller-image).
     - Alternatively, you can build an Ingress Controller image with NGINX Plus and push it to your private registry by following the instructions from [here](https://docs.nginx.com/nginx-ingress-controller/installation/building-ingress-controller-image).
     - Update the `controller.image.repository` field of the `values-plus.yaml` accordingly.
-  - If you’d like to use App Protect DoS, please install App Protect DoS Arbitrator helm chart. Make sure to install in the same namespace as the NGINX Ingress Controller. Note that if you install multiple NGINX Ingress Controllers in the same namespace, they will need to share the same Arbitrator because it is not possible to install more than one Arbitrator in a single namespace.
+  - If you’d like to use App Protect DoS, please install App Protect DoS Arbitrator [helm chart](https://github.com/nginxinc/nap-dos-arbitrator-helm-chart). Make sure to install in the same namespace as the NGINX Ingress Controller. Note that if you install multiple NGINX Ingress Controllers in the same namespace, they will need to share the same Arbitrator because it is not possible to install more than one Arbitrator in a single namespace.
 
 ## CRDs