fix Kubernetes slack invitation link in new contributor resources from "www.slack.k8s.io" to "slack.k8s.io"

Signed-off-by: Osama Nabih <[email protected]>

Author: OsamaNabih

mentoring/new-contributor-orientation/new-contributor-resources.md

@@ -4,7 +4,7 @@
 
 - Join the Kubernetes Developer Google Group (k-dev): [https://groups.google.com/a/kubernetes.io/g/dev](https://groups.google.com/a/kubernetes.io/g/dev)
 - Check out [kubernetes/community](https://github.com/kubernetes/community) for an overview of our community.
-- Come join us in the [Kubernetes Slack](https://www.slack.k8s.io):
+- Come join us in the [Kubernetes Slack](https://slack.k8s.io):
   - Join the #kubernetes-new-contributors channel
   - Join the channels of 1 or more SIGs you're interested in
 - Participate in the [New Contributor Orientation](./README.md) to get an introduction to Kubernetes development and the community.