docs(README): update app run instructions

- Move running instructions closer to the prerequisite section
- Improve formatting and readability of code examples
- Maintain note about backend service for development environment

Author: fulleni

README.md

@@ -87,23 +87,21 @@ Get started for free and purchase when you're ready to launch!
     ```
 4.  **Run the app:**
 
-### Running the App
+    To run the app, first select your desired environment in `lib/main.dart`:
 
-To run the app, first select your desired environment in `lib/main.dart`:
+    ```dart
+    // lib/main.dart
 
-```dart
-// lib/main.dart
-
-// Use `AppEnvironment.demo` to run with in-memory data (no API needed).
-// Use `AppEnvironment.development` to connect to a local backend API.
-const appEnvironment = AppEnvironment.demo; 
-```
+    // Use `AppEnvironment.demo` to run with in-memory data (no API needed).
+    // Use `AppEnvironment.development` to connect to a local backend API.
+    const appEnvironment = AppEnvironment.demo; 
+    ```
 
-Then, run the app from your terminal:
-```bash
-flutter run -d chrome
-```
-*(Note: For `development` environment, ensure the [backend service](https://github.com/flutter-news-app-full-source-code/flutter-news-app-api-server-full-source-code) is running.)*
+    Then, run the app from your terminal:
+    ```bash
+    flutter run -d chrome
+    ```
+    *(Note: For `development` environment, ensure the [backend service](https://github.com/flutter-news-app-full-source-code/flutter-news-app-api-server-full-source-code) is running.)*
 
 ---