docs(*): add RELEASE.md

Signed-off-by: Vaughn Dice <vdice@akamai.com>

Author: vdice

RELEASE.md

@@ -0,0 +1,43 @@
+# Runtime Class Manager release process
+
+The vast majority of the release process is handled by GitHub workflows triggered by a tag push.
+See [release.yaml](./.github/workflows/release.yml) for the main workflow.
+
+First, let's start by setting a `$TAG` environment variable to the version we'll release, so that we can reference it later.
+
+For example, if the most recent release was `v0.1.0` and subsequent changes on
+the `main` branch include the usual collection of patches, fixes and features,
+we'd cut `v0.2.0`:
+
+```console
+export TAG=v0.2.0 # CHANGEME
+```
+
+Next, be sure that CI is green for the current commit on the `main` branch.
+
+Then, to push the tag, do the following:
+
+```console
+git checkout main
+git remote add upstream git@github.com:spinframework/runtime-class-manager
+git pull upstream main
+git tag --sign $TAG --message "Runtime Class Manager $TAG"
+git push upstream $TAG
+```
+
+Observe that the [Release Workflow run for the tag](https://github.com/spinframework/runtime-class-manager/actions/workflows/release.yml) completed successfully.
+
+Next, you'll need to update the documentation:
+
+```console
+git clone git@github.com:spinframework/spinkube-docs
+cd spinkube-docs
+```
+
+Change all references from the previous version to the new version.
+
+Contribute those changes and open a PR.
+
+As an optional step, you can run a set of smoke tests to ensure the latest release works as expected.
+
+Finally, announce the new release on the #spinkube CNCF Slack channel.