docs(js): fix predictions setup example (#8153)

* fix predictions front end configuration example

* update pkg installation

src/pages/[platform]/build-a-backend/add-aws-services/predictions/set-up-predictions/index.mdx

@@ -145,21 +145,21 @@ backend.addOutput({
 To install the Amplify library to use predictions features, run the following commands in your project's root folder:
 
 ```bash title="Terminal" showLineNumbers={false}
-npm add aws-amplify
+npm add aws-amplify @aws-amplify/predictions
 ```
 
 ## Configure the frontend
 
 Import and load the configuration file in your app. It is recommended you add the Amplify configuration step to your app's root entry point. For example `main.ts` in React and Angular.
 
 ```ts title="src/main.ts"
-import { Predictions } from "aws-amplify/predictions";
+import { Amplify } from "aws-amplify";
 import outputs from "./amplify_outputs.json";
 
 Amplify.configure(outputs);
 
 Amplify.configure({
   ...Amplify.getConfig(),
-  Predictions: config.custom.Predictions,
+  Predictions: outputs.custom.Predictions,
 });
 ```