Add instructions for running project via GitHub Codespaces

Enhance README.md with detailed steps for running the project using GitHub Codespaces. Users now have an alternative option to develop and run the application directly from a cloud-based development environment.

README.md

@@ -24,6 +24,8 @@ Ensure that you have Devbox installed and configured. Devbox manages the depende
 
 ### Steps to Run
 
+#### Option 1: Locally
+
 1. **Clone the repository**
    ```bash
    git clone https://github.com/eth-library/devbox-spring-demo.git
@@ -44,6 +46,25 @@ Ensure that you have Devbox installed and configured. Devbox manages the depende
    ```bash
    curl "http://localhost:8080/greeting?name=Devbox%20Tester"
 
+#### Option 2: Using GitHub Codespaces
+
+1. Fork this repository
+
+2. From the **Code** dropdown, select **Create codespace on main**
+
+3. Once the codespace has loaded, run `devbox run start` in the terminal to start the webserver.
+
+    ```bash
+    devbox run start
+    ```
+
+4. When prompted, click **Open in Browser**.
+
+> [!TIP]
+> If the popup is not visible, you can navigate to the **Forwarded Ports** tab, and open the **Forwarded Address** for port 8080.
+
+5. **Success!** You'll see the landing page and can now curl the greeting endpoint!
+
 ## Custom Maven Settings
 
 To maintain an isolated environment, a custom `maven.config` file is provided in the `.mvn` directory. This configuration ensures that all Maven dependencies are stored locally within the project rather than in a global repository. This approach helps to keep the development environment fully isolated, avoiding any interference from global dependencies.