docs: sunset the docs/plugins section as legacy documentation

Mark all pages in docs/plugins/ with legacy admonition banners pointing
to the appropriate new frontend system and backend system documentation.
Rename the sidebar section to "Plugins (Legacy)" and move it lower in
the navigation hierarchy. Add cross-references from the new frontend
system building-plugins guide to relevant cross-cutting topics (i18n,
analytics, feature flags, search) that still live in the legacy section.

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor
This commit is contained in:
Patrik Oldsberg
2026-03-17 10:49:54 +01:00
parent 05594087b9
commit 35e130c601
22 changed files with 181 additions and 55 deletions
+6
View File
@@ -4,6 +4,12 @@ title: Composability System
description: Documentation for the Backstage plugin composability APIs.
---
:::caution Legacy Documentation
This page describes the composability system for the **old frontend system**, including `createRoutableExtension`, `createComponentExtension`, `RouteRef`, `ExternalRouteRef`, and component data. For the new frontend system, see [Extensions](../frontend-system/architecture/20-extensions.md), [Extension Blueprints](../frontend-system/architecture/23-extension-blueprints.md), and [Routes](../frontend-system/architecture/36-routes.md).
:::
## Summary
This page describes the composability system that helps bring together content