[OCM Incubation] Add a release runbook

[xuezhaojun]

[haoqing0110]

We already have this https://github.com/open-cluster-management-io/community/blob/main/release.md and need to update it.

[haoqing0110]

/assign @haoqing0110

[haoqing0110]

https://github.com/open-cluster-management-io/community/pull/208/files