Clarify release policy

Signed-off-by: Bogdan Dobrelya <bogdando@mail.ru>

RELEASE.md

@@ -7,3 +7,21 @@ The Kargo Project is released on an as-needed basis. The process is as follows:
 3. An OWNER runs `git tag -s $VERSION` and inserts the changelog and pushes the tag with `git push $VERSION`
 4. The release issue is closed
 5. An announcement email is sent to `kubernetes-dev@googlegroups.com` with the subject `[ANNOUNCE] kargo $VERSION is released`
+
+## Major/minor releases, merge freezes and milestones
+
+* Kargo does not maintain stable branches for releases. Releases are tags, not
+  branches, and there are no backports. Therefore, there is no need for merge
+  freezes as well.
+
+* Fixes for major releases (vX.Y.0) are delivered via minor releases (vX.Y.Z)
+  and assigned to the corresponding open milestone (vX.Y). That milestone
+  remains open for the release support lifetime, which ends once the milestone
+  closed. Then only a next major release can be done.
+
+* Kargo major releases are bound to the given ``kube_version`` and other components'
+  versions, like etcd or network plugins. Older or newer versions are not
+  supported and not tested for the given release.
+
+* Minor releases can change components' versions, but not the ``kube_version``.
+  Greater ``kube_version`` requires a new major release.