docs: address copilot review feedback

Fix links in viewing-catalog.md and filter-catalog.md to point to
the new frontend system catalog-customization.md instead of the old
guide. Fix the Kubernetes entity content extension ID to use the
correct `entity-content:kubernetes/kubernetes` format. Wrap raw
extension definitions in `createFrontendModule` in search and
scaffolder docs. Correct TechDocs addon installation instructions
to explicitly install addon modules rather than claiming
auto-discovery.

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor

docs/features/kubernetes/installation.md

@@ -24,7 +24,7 @@ The Kubernetes tab is shown by default for entities where Kubernetes data is ava
 ```yaml title="app-config.yaml"
 app:
   extensions:
-    - entity-content:kubernetes:
+    - entity-content:kubernetes/kubernetes:
         config:
           filter:
             metadata.annotations.backstage.io/kubernetes-id:

docs/features/search/getting-started.md

@@ -119,14 +119,24 @@ export const MySearchResultListItem = SearchResultListItemBlueprint.make({
 });
 ```
 
-Install this in your app by passing it to `createApp`:
+Install this in your app by wrapping it in a frontend module and passing it to `createApp`:
+
+```tsx title="packages/app/src/search/searchModule.ts"
+import { createFrontendModule } from '@backstage/frontend-plugin-api';
+import { MySearchResultListItem } from './MySearchResultListItem';
+
+export const searchCustomizations = createFrontendModule({
+  pluginId: 'search',
+  extensions: [MySearchResultListItem],
+});
+```
 
 ```tsx title="packages/app/src/App.tsx"
 import { createApp } from '@backstage/frontend-defaults';
-import { MySearchResultListItem } from './search/MySearchResultListItem';
+import { searchCustomizations } from './search/searchModule';
 
 const app = createApp({
-  features: [MySearchResultListItem],
+  features: [searchCustomizations],
 });
 
 export default app.createRoot();

docs/features/search/how-to-guides.md

@@ -178,14 +178,24 @@ The extension is then exported from your plugin's alpha entry point and
 automatically discovered when the plugin is installed.
 
 If you need to provide a search result list item extension from your app
-rather than a plugin, you can install it directly in `createApp`:
+rather than a plugin, wrap it in a frontend module and pass it to `createApp`:
+
+```tsx title="packages/app/src/search/searchModule.ts"
+import { createFrontendModule } from '@backstage/frontend-plugin-api';
+import { YourSearchResultListItem } from './YourSearchResultListItem';
+
+export const searchCustomizations = createFrontendModule({
+  pluginId: 'search',
+  extensions: [YourSearchResultListItem],
+});
+```
 
 ```tsx title="packages/app/src/App.tsx"
 import { createApp } from '@backstage/frontend-defaults';
-import { YourSearchResultListItem } from './search/YourSearchResultListItem';
+import { searchCustomizations } from './search/searchModule';
 
 const app = createApp({
-  features: [YourSearchResultListItem],
+  features: [searchCustomizations],
 });
 
 export default app.createRoot();

docs/features/software-templates/writing-custom-field-extensions.md

@@ -117,14 +117,24 @@ export const ValidateKebabCaseFieldExtension = FormFieldBlueprint.make({
 export { ValidateKebabCaseFieldExtension } from './extensions';
 ```
 
-Once the extension is created, install it in your app by passing it to `createApp`:
+Once the extension is created, install it in your app by wrapping it in a frontend module and passing it to `createApp`:
+
+```tsx title="packages/app/src/scaffolder/scaffolderModule.ts"
+import { createFrontendModule } from '@backstage/frontend-plugin-api';
+import { ValidateKebabCaseFieldExtension } from './ValidateKebabCase';
+
+export const scaffolderCustomizations = createFrontendModule({
+  pluginId: 'scaffolder',
+  extensions: [ValidateKebabCaseFieldExtension],
+});
+```
 
 ```tsx title="packages/app/src/App.tsx"
 import { createApp } from '@backstage/frontend-defaults';
-import { ValidateKebabCaseFieldExtension } from './scaffolder/ValidateKebabCase';
+import { scaffolderCustomizations } from './scaffolder/scaffolderModule';
 
 const app = createApp({
-  features: [ValidateKebabCaseFieldExtension],
+  features: [scaffolderCustomizations],
 });
 
 export default app.createRoot();

docs/features/techdocs/getting-started.md

@@ -29,15 +29,30 @@ The plugin provides a docs index page at `/docs` and a reader page for individua
 
 ## Using TechDocs Addons
 
-The TechDocs Addon framework lets you render React components in documentation pages. Addons are provided as separate plugin packages that are automatically discovered when installed.
+The TechDocs Addon framework lets you render React components in documentation pages. Addons are provided as separate plugin modules.
 
-For example, to add the Report Issue addon:
+For example, to add the Report Issue addon, first install the package:
 
 ```bash title="From your Backstage root directory"
 yarn --cwd packages/app add @backstage/plugin-techdocs-module-addons-contrib
 ```
 
-Once installed, the addon is automatically active. You can see it in action when you highlight text in your documentation:
+Then install the addon module in your app:
+
+```tsx title="packages/app/src/App.tsx"
+import { createApp } from '@backstage/frontend-defaults';
+import { techDocsReportIssueAddonModule } from '@backstage/plugin-techdocs-module-addons-contrib/alpha';
+
+const app = createApp({
+  features: [techDocsReportIssueAddonModule],
+});
+
+export default app.createRoot();
+```
+
+The same package also provides `techDocsExpandableNavigationAddonModule`, `techDocsTextSizeAddonModule`, and `techDocsLightBoxAddonModule`.
+
+You can see the Report Issue addon in action when you highlight text in your documentation:
 
 <!-- todo: Needs zoomable plugin -->