Merge pull request #3102 from mrbobbytables/update-kusers-links

Replace kubernetes-users mailing list links with discuss forum link

CONTRIBUTING.md

@@ -38,6 +38,6 @@ Whether you are a user or contributor, official support channels include:
 
 - GitHub issues: https://github.com/kubernetes/ingress-nginx/issues/new
 - Slack: kubernetes-users room in the [Kubernetes Slack](http://slack.kubernetes.io/)
-- Email: [kubernetes-users](https://groups.google.com/forum/#!forum/kubernetes-users) mailing list
+- Post: [Kubernetes Forum](https://discuss.kubernetes.io)
 
 Before opening a new issue or submitting a new pull request, it's helpful to search the project - it's likely that another user has already reported the issue you're facing, or it's a known issue that we're already aware of.

README.md

@@ -41,7 +41,7 @@ To check out [Live Docs](https://kubernetes.github.io/ingress-nginx/)
 
 ## Questions
 
-For questions and support please use the [#ingress-nginx](https://kubernetes.slack.com/messages/CANQGM8BA/) channel in the [Kubernetes Slack](http://slack.kubernetes.io/) or [kubernetes-users](https://groups.google.com/forum/#!forum/kubernetes-users) mailing list. The issue list of this repo is **exclusively** for bug reports and feature requests.
+For questions and support please use the [#ingress-nginx](https://kubernetes.slack.com/messages/CANQGM8BA/) channel in the [Kubernetes Slack](http://slack.kubernetes.io/) or post to the [Kubernetes Forum](https://discuss.kubernetes.io). The issue list of this repo is **exclusively** for bug reports and feature requests.
 
 ## Issues