simplify vapid key generation docs (#72916)

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### What?

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Closes NEXT-
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### What?
Simplify Vapid key generation docs

### Why?
Creating a script is tedious.
The CLI can be used across projects without needing to reference and
recreate this script.

### How?
Added instructions to install `web-push` globally and how to run it.

---------

Co-authored-by: Delba de Oliveira <[email protected]>

docs/01-app/02-building-your-application/07-configuring/16-progressive-web-apps.mdx

@@ -508,27 +508,26 @@ In a production environment, you would want to store the subscription in a datab
 
 ### 4. Generating VAPID Keys
 
-To use the Web Push API, you need to generate [VAPID](https://vapidkeys.com/) keys.
+To use the Web Push API, you need to generate [VAPID](https://vapidkeys.com/) keys. The simplest way is to use the web-push CLI directly:
 
-Create a script file, e.g., `generate-vapid-keys.js`:
+First, install web-push globally:
 
-```js filename="./generate-vapid-keys.js"
-const webpush = require('web-push')
-const vapidKeys = webpush.generateVAPIDKeys()
-
-console.log('Paste the following keys in your .env file:')
-console.log('-------------------')
-console.log('NEXT_PUBLIC_VAPID_PUBLIC_KEY=', vapidKeys.publicKey)
-console.log('VAPID_PRIVATE_KEY=', vapidKeys.privateKey)
+```bash filename="Terminal"
+npm install -g web-push
 ```
 
-Run this script with Node.js to generate your VAPID keys:
+Generate the VAPID keys by running:
 
 ```bash filename="Terminal"
-node generate-vapid-keys.js
+web-push generate-vapid-keys
 ```
 
-Copy the output and paste it into your `.env` file.
+Copy the output and paste the keys into your `.env` file:
+
+```.env
+NEXT_PUBLIC_VAPID_PUBLIC_KEY=your_public_key_here
+VAPID_PRIVATE_KEY=your_private_key_here
+```
 
 ### 5. Creating a Service Worker