Fix name and link to k8s oncall.
Fix name and link to k8s oncall.

https://github.com/k8s-oncall works
https://github.com/search?q=k8s-support-oncall&type=Users&utf8=%E2%9C%93
shows no matches, and https://github.com/k8s-support-oncall is a 404.

I guess this is another call for #359.

bgrant0607/community,pwittrock/community,kubernetes/community,kubernetes/community,pwittrock/community,bgrant0607/community,kubernetes/community