feat(core-plugin-api): add optional description to plugin feature flags

Signed-off-by: ElaineDeMattosSilvaB <elaine.de-mattos-silva-bezerra@deutschebahn.com>

.changeset/eager-toes-rest.md

@@ -0,0 +1,23 @@
+---
+'@backstage/core-plugin-api': patch
+'@backstage/core-app-api': patch
+---
+
+Add optional `description` field to plugin-level feature flags.
+
+Plugin developers can now provide an optional description for their feature flags:
+
+```ts
+export const myPlugin = createPlugin({
+  id: 'my-plugin',
+  featureFlags: [
+    {
+      name: 'show-beta-feature',
+      description: 'Enables the new beta dashboard view',
+    },
+  ],
+});
+
+If no description is provided, the default "Registered in {pluginId} plugin" message is shown.
+
+```

packages/core-app-api/src/app/AppManager.tsx

@@ -336,6 +336,7 @@ DEPRECATION WARNING: React Router Beta is deprecated and support for it will be
               for (const flag of plugin.getFeatureFlags()) {
                 featureFlagsApi.registerFlag({
                   name: flag.name,
+                  description: flag.description,
                   pluginId: plugin.getId(),
                 });
               }

packages/core-plugin-api/src/plugin/types.ts

@@ -73,6 +73,8 @@ export type BackstagePlugin<
 export type PluginFeatureFlagConfig = {
   /** Feature flag name */
   name: string;
+  /** Feature flag description */
+  description?: string;
 };
 
 /**