* Creates staging directory for common controller-manager code
* Adds the following initial files to this directory:
* .github/PULL_REQUEST_TEMPLATE.md
* code-of-conduct.md
* LICENSE
* OWNERS
* README.md
* SECURITY_CONTACTS
* Code committed to the controller-manager staging directory will be published to: https://github.com/kubernetes/controller-manager
Initial approval deads2k (sig-api-machinery chair)
The config we would expect any controller manager to need to connect to the API server, set up metrics endpoints, create per-controller-loop API clients, and spin up the individual loops could make sense under a k8s.io/controller-manager package.
Then cmd/kube-controller-manager could continue to contain the weirdnesses specific to kube-controller-manager.
This is similar to the way we split out recommended API server setup into k8s.io/apiserver and tried to limit kube-apiserver oddities to cmd/kube-apiserver and pkg/kubeapiserver
Removed extraneous release reference. Ran update-vendor.
Fixed Readme.
Added a doc.go to staging/controller-manager
Fix package to not have dash.
```
NONE
```
/kind cleanup
/sig api-machinery
/area kube-controller-manager
/area cloud-controller-manager
