docs: Update README of sample app to include prerequisites section (#652)

* Update README of sample app to include prerequisites section

* Update sample-code/spring-app/README.md

---------

Co-authored-by: Matthias Kuhr <52661546+MatKuhr@users.noreply.github.com>

Author: modood-alvi

sample-code/spring-app/README.md

@@ -5,6 +5,29 @@
 Sample code to demonstrate the usage of the SAP AI SDK.
 Also used as basis for running E2E tests.
 
+## Prerequisites
+
+Before running the application, ensure the following prerequisites are met:
+
+- Java 17 or higher
+- Maven 3.8 or higher
+- Credentials for [SAP AI Core](https://help.sap.com/docs/sap-ai-core/sap-ai-core-service-guide/what-is-sap-ai-core) service configured
+- Deployments of the following models in the `default` resource group:
+  - `gpt-4o-mini`
+  - `text-embedding-3-small`
+
+### Setting Up Credentials for SAP AI Core
+
+To set up credentials for the AI Core service:
+
+- Follow the instruction at [Connecting to AI Core](https://sap.github.io/ai-sdk/docs/java/guides/connecting-to-ai-core) to create a service key for the AI Core service.
+- Add the service key content either to a `.env` file in the sample app directory or directly to the `AI_CORE_SERVICE_KEY` environment variable.
+
+### Deploying Generative AI Models in SAP AI Core
+
+To deploy `gpt-4o-mini` and `text-embedding-3-small` models, follow the instructions at:
+[Create a Deployment for a Generative AI Model](https://help.sap.com/docs/sap-ai-core/sap-ai-core-service-guide/create-deployment-for-generative-ai-model-in-sap-ai-core)
+
 ## Build and Run the Sample App
 
 Before you can run the sample app, you need to install the AI SDK into your local Maven repository:
@@ -15,13 +38,7 @@ Before you can run the sample app, you need to install the AI SDK into your loca
 > The sample app uses the latest state of the SDK, so make sure to install the SDK after pulling a new version via Git.
 > Alternatively, you check out one of the release tags of the repository, e.g. `git fetch --all --tags && git checkout rel/1.1.0`. 
 
-Next, you'll need to set up credentials for the AI Core service: 
-
-* Follow [these instructions](https://sap.github.io/ai-sdk/docs/java/guides/connecting-to-ai-core) to create a service key for the AI Core service.
-
-  ⚠️ Put the `.env` file in the sample app directory.
-
-Finally, you can start the sample app:
+Start the sample app:
 
 * Run `mvn spring-boot:run` from the sample app directory.