Details about semver of the recipe

Spell out how we update the release versions of the recipe, specifically
wrt dependencies.

MAINTENANCE.md

@@ -38,7 +38,7 @@ In order to meet these responsibilities each maintainer:
 ## Release cadence
 
 The intent is to **track Nextcloud's own release schedule** rather than invent
-our own. In practice this means:
+our own. In practice this means the following regarding new **nextcloud** releases:
 
 - **Patch releases (e.g. `32.0.x`)**: published to this recipe shortly after
   upstream, ideally within 1 week. `chore(deps)` opens the PRs; a maintainer
@@ -63,6 +63,23 @@ our own. In practice this means:
 - **Co-installed components** (Talk HPB, OnlyOffice, Whiteboard, etc.) are
   bumped alongside or shortly after the matching Nextcloud release.
 
+## Semver versioning within this recipe
+
+The recipe version itself is updated according to the following semver
+rules, following
+[How are recipes versioned](https://docs.coopcloud.tech/maintainers/handbook/#how-are-recipes-versioned):
+
+- **Patch releases**, e.g., 14.1.x: patch updates from the dependencies
+  or patch updates from the nextcloud image
+- **Minor releases**, e.g. 14.x.0: minor updates from the dependencies,
+  major updates from the dependencies if no user intervention is needed,
+  minor updates from the nextcloud image, or "auto-update" version, e.g.,
+  nextcloud:32. 
+  Contrary to patch releases, minor releases cannot be reverted, so you
+  cannot go from 14.1.0 back to 14.0.1.
+- **Major releases**, e.g., 14: dependency updates where the user has to
+  intervene, or major updates from the nextcloud image.
+
 ## Pull Requests
 
 A pull request can be merged once it is approved by at least one maintainer.