Merge pull request #57571 from spiffxp/mk-staging-repos-authoritative

Automatic merge from submit-queue (batch tested with PRs 58025, 57112, 57879, 57571, 58062). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Treat staging repos as authoritative source for all files

Add CONTRIBUTING.md files to remind people not to PR directly into the published repos.

/hold
I believe this requires removing these files from the published repos if any copies exist there

ref: kubernetes/kubernetes#57559

Kubernetes-commit: 4bc286f0255d6c007cb8d5435018ab3e31ec7d01

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,2 @@
+Sorry, we do not accept changes directly against this repository. Please see 
+CONTRIBUTING.md for information on where and how to contribute instead.

CONTRIBUTING.md

@@ -0,0 +1,7 @@
+# Contributing guidelines
+
+Do not open pull requests directly against this repository, they will be ignored. Instead, please open pull requests against [kuberentes/kubernetes](https://git.k8s.io/kubernetes/).  Please follow the same [contributing guide](https://git.k8s.io/kubernetes/CONTRIBUTING.md) you would follow for any other pull request made to kubernetes/kubernetes.
+
+This repository is published from [kubernetes/kubernetes/staging/src/k8s.io/client-go](https://git.k8s.io/kubernetes/staging/src/k8s.io/client-go) by the [kubernetes publishing-bot](https://git.k8s.io/publishing-bot). 
+
+Please see [Staging Directory and Publishing](https://git.k8s.io/community/contributors/devel/staging.md) for more information