Add LocalStack for AWS license requirement (#6)

* Add LocalStack for AWS license requirement to prerequisites

* Update README.md

* Hyperlink LOCALSTACK_AUTH_TOKEN in license prerequisite

* Add auth token guard to start target

Author: HarshCasper

Makefile

@@ -38,6 +38,7 @@ deploy:			## Deploy all solutions
 	@echo "All solutions deployed successfully."
 
 start:			## Start localstack
+	@test -n "${LOCALSTACK_AUTH_TOKEN}" || (echo "LOCALSTACK_AUTH_TOKEN is not set. Find your token at https://app.localstack.cloud/workspace/auth-token"; exit 1)
 	LOCALSTACK_AUTH_TOKEN=$(LOCALSTACK_AUTH_TOKEN) docker compose up --build --detach --wait
 
 stop:			## Stop localstack

README.md

@@ -47,7 +47,7 @@ The following diagram shows the architecture that this sample application builds
 
 ## Prerequisites
 
-- [`LOCALSTACK_AUTH_TOKEN`](https://docs.localstack.cloud/getting-started/auth-token/)
+- A valid [LocalStack for AWS license](https://localstack.cloud/pricing). Your license provides a [`LOCALSTACK_AUTH_TOKEN`](https://docs.localstack.cloud/getting-started/auth-token/) to activate LocalStack.
 - [Docker](https://docs.docker.com/get-docker/) and [Docker Compose](https://docs.docker.com/compose/install/)
 - [AWS CLI](https://docs.localstack.cloud/user-guide/integrations/aws-cli/) with the [`awslocal` wrapper](https://docs.localstack.cloud/user-guide/integrations/aws-cli/#localstack-aws-cli-awslocal)
 - [Maven 3.8.5+](https://maven.apache.org/install.html) & [Java 17](https://www.java.com/en/download/help/download_options.html)