chore: fix backend-test-utils changeset

Signed-off-by: benjdlambert <ben@blam.sh>

.changeset/sweet-ducks-wait.md

@@ -2,4 +2,29 @@
 '@backstage/backend-test-utils': minor
 ---
 
-Added mock implementations for `ActionsService` and `ActionsRegistryService`
+Added an `actionsRegistryServiceMock` and `actionsServiceMock` to `/alpha` export for the experimental services.
+
+This allows you to write tests for your actions by doing something similar to the following:
+
+```ts
+import { actionsRegistryServiceMock } from '@backstage/backend-test-utils/alpha`;
+
+const mockActionsRegistry = actionsRegistryServiceMock();
+const mockCatalog = catalogServiceMock({
+  entities: [
+   ...
+  ],
+});
+
+createGetCatalogEntityAction({
+  catalog: mockCatalog,
+  actionsRegistry: mockActionsRegistry,
+});
+
+await expect(
+  mockActionsRegistry.invoke({
+    id: 'test:get-catalog-entity',
+    input: { name: 'test' },
+  }),
+).resolves.toEqual(...)
+```