[TASK] Update documentation for new major LTS version

Documentation/Maintainers/NewMajorCoreVersion.rst

@@ -1,22 +1,120 @@
 ..  include:: /Includes.rst.txt
 ..  _new-major-core-versions:
 
-==================================
-New major Core version is released
-==================================
+=================================================
+Branching of the docs for a new major LTS version
+=================================================
 
 ..  contents::
 
+Create branches for the new LTS version in all versioned official repositories
+==============================================================================
+
+This includes all manuals in the "All Documentation" menu with version hints,
+excluding the System extension manuals. The System extension manuals will
+receive their new versions automatically via webhook in the release. This might
+take a few days.
+
+*   Create a new branch. `14.3` in this example.
+*   Limit the composer.json to that version. For example `"typo3/cms-core": "^14.3"`
+    instead of `"typo3/cms-core": "dev-main as 14.3"` and make sure `composer update`
+    works.
+*   Set the release and version to the new minor version, for example
+
+    ..  code-block:: xml
+        :caption: Documentation/guides.xml
+
+        <project title="TYPO3 Explained"
+                 release="14.3"
+                 version="14.3"
+                 copyright="since 2012 by the TYPO3 contributors"
+        />
+
+**After all the new LTS branches have been created and rendered** for all repositories,
+revisit the guides.xml in all new LTS branches and raise to the preferred typo3 version:
+
+..  code-block:: xml
+    :caption: Documentation/guides.xml
+    :emphasize-lines: 9
+
+    <extension
+        class="\T3Docs\Typo3DocsTheme\DependencyInjection\Typo3DocsThemeExtension"
+        project-home="https://docs.typo3.org/m/typo3/reference-coreapi/main/en-us/"
+        project-contact="https://typo3.slack.com/archives/C028JEPJL"
+        project-repository="https://github.com/TYPO3-Documentation/TYPO3CMS-Reference-CoreApi"
+        project-issues="https://github.com/TYPO3-Documentation/TYPO3CMS-Reference-CoreApi/issues"
+        edit-on-github-branch="main"
+        edit-on-github="TYPO3-Documentation/TYPO3CMS-Reference-CoreApi"
+        typo3-core-preferred="14.3"
+        interlink-shortcode="t3coreapi"
+    />
+
+We usually leave the `edit-on-github-branch` on main to avoid people making PRs
+against the LTS branch and to avoid confusion in our backport workflows.
+
+..  _new-major-core-versions-elts:
+
+Add new eLTS warnings to the newly created eLTS version
+=======================================================
+
+Add a warning to the `Documentation/Includes.rst.txt` of the branch for the
+new eLTS versions of all repositories:
+
+..  code-block:: rst
+    :caption: Documentation/Includes.rst.txt
+
+    ..  You can put central messages to display on all pages here
+
+    ..  attention::
+        TYPO3 v11 has reached end-of-life as of April 30th 2026 and
+        is no longer being maintained. Use the version switcher on the top
+        left of this page to select documentation for a supported version of TYPO3.
+
+        Need more time before upgrading?
+        You can purchase Extended Long Term Support (ELTS) for TYPO3 v12 here:
+        `TYPO3 ELTS <https://typo3.com/services/extended-support-elts>`__.
+
+..  _new-major-core-versions-startpage:
+
+Update the start page docs.typo3.org for a new major version
+============================================================
+
+*   Add the new major version to the main menu:
+    https://github.com/TYPO3-Documentation/DocsTypo3Org-Homepage/blob/main/Documentation/_mainMenu.rst.txt
+    Remove the versions that are now ELTS.
+*   Add the new API version to the main menu
+*   Require the latest LTS version in
+    https://github.com/TYPO3-Documentation/DocsTypo3Org-Homepage/blob/main/composer.json
 
 ..  _new-major-core-versions-api:
 
 Update api.typo3.org for a new major version
 ============================================
 
-*  Add the new TYPO3 LTS version for rendering into 
+*  Add the new TYPO3 LTS version for rendering into
    https://github.com/TYPO3-Documentation/t3docs-ci-deploy/blob/main/.github/workflows/api-typo3-org.yml#L13
-*  Add the new TYPO3 Version to the sidebar of api.typo3.org: 
+*  Add the new TYPO3 version to the sidebar of api.typo3.org:
    https://github.com/TYPO3-Documentation/render-guides/blob/main/packages/typo3-api/template/components/sidebar.html.twig#L9
-*  Trigger rendering of the api, by triggering above workflow
-*  Add the new version to the api.typo3.org startpage: https://github.com/TYPO3-Documentation/DocsTypo3Org-Homepage/blob/main/WebRootResources-api.typo3.org/index.html
-*  Add the new Version to the main Menu: http://github.com/TYPO3-Documentation/DocsTypo3Org-Homepage/blob/main/Documentation/_mainMenu.rst.txt
+*  Trigger rendering of the API by running the workflow above
+*  Add the new version to the api.typo3.org start page: https://github.com/TYPO3-Documentation/DocsTypo3Org-Homepage/blob/main/WebRootResources-api.typo3.org/index.html
+*  Add the new version to the main menu: http://github.com/TYPO3-Documentation/DocsTypo3Org-Homepage/blob/main/Documentation/_mainMenu.rst.txt
+
+..  _new-major-core-versions-renderguides:
+
+Set the "stable" version for links to the new LTS version in renderguides
+=========================================================================
+
+You should only do this after all versioned repositories exist in the new LTS
+version and have been rendered; otherwise, rendering links will fail in all
+manuals that are newly rendered. Then create a new renderguides release by
+creating a tag for the version. See https://github.com/TYPO3-Documentation/render-guides/pull/1246
+for an example.
+
+..  _new-major-core-versions-search:
+
+Make the new LTS version the preferred result in the docs search
+================================================================
+
+Require the newly created version of `t3docs/typo3-version-handling`
+(created by the renderguides release in https://github.com/TYPO3-Documentation/t3docs-search-indexer)
+and make a new release of the search.