feat(serialization): Update documentation and makefile

Author: jreijn

examples/powertools-examples-serialization/sam-graalvm/Makefile

@@ -1,12 +1,12 @@
 build-APIGatewayDeserializationFunction:
-	#mvn clean package -P native-image
+	mvn clean package -P native-image
 	chmod +x target/hello-world
 	cp target/hello-world $(ARTIFACTS_DIR) # (ARTIFACTS_DIR --> https://github.com/aws/aws-lambda-builders/blob/develop/aws_lambda_builders/workflows/custom_make/DESIGN.md#implementation)
 	chmod +x src/main/config/bootstrap
 	cp src/main/config/bootstrap $(ARTIFACTS_DIR)
 
 build-SQSEventDeserializationFunction:
-	#mvn clean package -P native-image
+	mvn clean package -P native-image
 	chmod +x target/hello-world
 	cp target/hello-world $(ARTIFACTS_DIR) # (ARTIFACTS_DIR --> https://github.com/aws/aws-lambda-builders/blob/develop/aws_lambda_builders/workflows/custom_make/DESIGN.md#implementation)
 	chmod +x src/main/config/bootstrap

examples/powertools-examples-serialization/sam-graalvm/README.md

@@ -23,6 +23,40 @@ in JSON looks like this:
 This sample is based on Serverless Application Model (SAM). To deploy it, check out the instructions for getting
 started with SAM in [the examples directory](../../README.md)
 
+## Configuration
+
+- Set the environment to use GraalVM
+
+```shell
+export JAVA_HOME=<path to GraalVM>
+```
+
+## Build the sample application
+
+- Build the Docker image that will be used as the environment for SAM build:
+
+```shell
+docker build --platform linux/amd64 . -t powertools-examples-serialization-sam-graalvm
+```
+
+- Build the SAM project using the docker image
+
+```shell
+sam build --use-container --build-image powertools-examples-serialization-sam-graalvm
+```
+
+#### [Optional] Building with -SNAPSHOT versions of PowerTools
+
+- If you are testing the example with a -SNAPSHOT version of PowerTools, the maven build inside the docker image will fail. This is because the -SNAPSHOT version of the PowerTools library that you are working on is still not available in maven central/snapshot repository.
+  To get around this, follow these steps:
+    - Create the native image using the `docker` command below on your development machine. The native image is created in the `target` directory.
+        - `` docker run --platform linux/amd64  -it -v `pwd`:`pwd` -w `pwd` -v ~/.m2:/root/.m2 powertools-examples-serialization-sam-graalvm mvn clean -Pnative-image package -DskipTests ``
+    - Edit the [`Makefile`](Makefile) remove this line
+        - `mvn clean package -P native-image`
+    - Build the SAM project using the docker image
+        - `sam build --use-container --build-image powertools-examples-serialization-sam-graalvm`
+
+
 ## Test the application
 
 ### 1. API Gateway Endpoint