fix empty schema on getting started manual installation page (#7995)

* fix empty schema on getting started manual installation page

* removed accidental yarn edit commit to package.json

* removed comment noting schemas cannot be empty

Author: svidgen

src/pages/[platform]/start/manual-installation/index.mdx

@@ -118,7 +118,13 @@ Or define your data resource:
 ```ts title="amplify/data/resource.ts"
 import { a, defineData, type ClientSchema } from '@aws-amplify/backend';
 
-const schema = a.schema({});
+const schema = a.schema({
+  Todo: a.model({
+      content: a.string(),
+      isDone: a.boolean()
+    })
+    .authorization(allow => [allow.publicApiKey()])
+});
 
 export type Schema = ClientSchema<typeof schema>;
 export const data = defineData({