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
@@ -238,3 +238,12 @@ export const examplePlugin = createFrontendPlugin({
The `ExampleEntityContent` itself is again a regular React component where you can implement any functionality you want. To access the entity that the content is being rendered for, you can use the `useEntity` hook from `@backstage/plugin-catalog-react`. You can see a full list of APIs provided by the catalog React library in [the API reference](https://backstage.io/api/stable/modules/_backstage_plugin-catalog-react.index.html).
For a more complete list of the different kinds of extensions that you can create for your plugin, see the [extension blueprints](./03-common-extension-blueprints.md) section.
## Related topics
The following guides cover cross-cutting concerns that apply to both the old and new frontend systems:
- [Internationalization (i18n)](../../plugins/internationalization.md) — Adding translations to your plugin using `createTranslationRef` and `useTranslationRef`.
- [Plugin Analytics](../../plugins/analytics.md) — Instrumenting user interactions with the Analytics API, including the `AnalyticsImplementationBlueprint` for the new frontend system.
- [Feature Flags](../../plugins/feature-flags.md) — Defining and using feature flags. In the new frontend system, flags are declared in the `featureFlags` option of `createFrontendPlugin`.
- [Integrating Search into Plugins](../../plugins/integrating-search-into-plugins.md) — Building search experiences and collators. For the new frontend system, use `SearchResultListItemBlueprint` from `@backstage/plugin-search-react/alpha`.