docs: fix typo in curl command example (#8071)

## Documentation Typo Fix: curl Command for Testing Service

This pull request addresses a typo in the documentation for testing the service via curl command on the page: [https://docs.medusajs.com/v2/basics/modules-and-services](https://docs.medusajs.com/v2/basics/modules-and-services)

**Initial Command (incorrect):**

```
curl http://locahost:9000/store/custom
```

**Corrected Command:**

```
curl http://localhost:9000/store/custom
```

The typo involved a missing "l" in "localhost". This fix ensures users can successfully test the service by providing the correct curl command.

www/apps/book/app/basics/modules-and-services/page.mdx

@@ -118,7 +118,7 @@ npm run dev
 Finally, send a `GET` request to `/store/custom`:
 
 ```bash apiTesting testApiUrl="http://localhost:9000/store/custom" testApiMethod="GET"
-curl http://locahost:9000/store/custom
+curl http://localhost:9000/store/custom
 ```
 
 You’ll receive the following response: