docs: Expand release procedure doc (#3009)

Note the requirement to bump container images as well as go package
versions.

Signed-off-by: Stephen Finucane <[email protected]>

Author: stephenfin

docs/release-procedure.md

@@ -1,8 +1,63 @@
 # Release Procedure
 
-The Cloud Provider OpenStack Release is done in sync with
-kubernetes/kubernetes. Minor versions can be released intermittently for
-critical bug fixes.
+Major versions of OpenStack Cloud Provider are done in sync with
+[kubernetes/kubernetes](https://github.com/kubernetes/kubernetes).
+Minor versions can be released intermittently for critical bug fixes.
+
+## Preparing for a release
+
+Note that while we use the terms *major* and *minor* here and below, these
+actually correspond to SemVer *minor* and *patch* versions. This is discussed
+in detail in [the Kubernetes documentation](https://github.com/kubernetes/sig-release/blob/master/release-engineering/versioning.md#kubernetes-release-versioning).
+
+### Major releases (`X.Y.0`)
+
+The following steps can be submitted as separate commits in a single PR or as
+separate PRs:
+
+1. Bump the version of the sidecar container images used in both the manifests
+   and Helm Charts.
+
+    You should pay particular attention to any major version bumps, since they
+    may require additional changes to the manifests or charts.
+
+    Example: https://github.com/kubernetes/cloud-provider-openstack/pull/3008
+
+2. (Optional) Bump any major, non-kubernetes dependencies
+
+    You may wish to bump the version of important dependencies like
+    `github.com/gophercloud/gophercloud` before bumping the version of
+    `k8s.io/kubernetes`.
+
+2. Bump the version of `k8s.io/kubernetes` to the latest minor version.
+
+    ```bash
+    go get -u k8s.io/kubernetes@latest
+    ```
+
+    Note that this will frequently bring in a new Go version corresponding to
+    the latest and greatest version. It will also automatically bump most of
+    the other dependencies from `k8s.io` to the same version. However, you must
+    manually bump the dependencies in the `replace` directive, once again using
+    the same version as `k8s.io/kubernetes`. Once done, you can confirm that
+    they are valid and that are none are missing by running `go list -m all`.
+    You may also wish to ensure that none are unnecessary by temporarily
+    deleting the `replace` directive and comparing the list of packages in the
+    output with the list of packages in the replace directive.
+
+    Example: https://github.com/kubernetes/cloud-provider-openstack/pull/3010
+
+3. Bump remaining dependencies.
+
+    Once again, pay close attention to any major version bumps of packages,
+    ensuring API changes are accounted for.
+
+### Minor releases (`X.Y.Z`, `Z` > 0)
+
+The release process for a minor release is effectively the same as the release
+process for major releases. However, you should only bump the *patch* version of
+`k8s.io/kubernetes` and avoid bumping the *major* version of any other
+dependency or sidecar container.
 
 ## Making a Release