Merge pull request #9004 from fricklerhandwerk/release-support

add information on release cycle and backports

doc/manual/src/release-notes/release-notes.md

@@ -1 +1,12 @@
 # Nix Release Notes
+
+Nix has a release cycle of roughly 6 weeks.
+Notable changes and additions are announced in the release notes for each version.
+
+Bugfixes can be backported on request to previous Nix releases.
+We typically backport only as far back as the Nix version used in the latest NixOS release, which is announced in the [NixOS release notes](https://nixos.org/manual/nixos/stable/release-notes.html#ch-release-notes).
+
+Backports never skip releases.
+If a feature is backported to version `x.y`, it must also be available in version `x.(y+1)`.
+This ensures that upgrading from an older version with backports is still safe and no backported functionality will go missing.
+