BAEL-2275: Move docker directory to test resources. Add README.md for it.

ddd/docker/.env

@@ -1 +0,0 @@
-ORDER_DOCKER_MONGODB_PORT=27017

ddd/src/test/resources/com/baeldung/dddhexagonalspring/README.md

@@ -0,0 +1,7 @@
+## Setup DDD Hexagonal Spring Application
+
+To run this project, follow these steps:
+
+* Launch the Spring Boot Application (DomainLayerApplication). 
+* Run the application database by executing `docker-compose up` in this directory.
+* By default, application will connect to this database (configuration in *ddd-layers.properties*)

ddd/src/test/resources/com/baeldung/dddhexagonalspring/docker-compose.yml

@@ -5,7 +5,7 @@ services:
     image: mongo:3.4.13
     restart: always
     ports:
-      - ${ORDER_DOCKER_MONGODB_PORT}:27017
+      - 27017:27017
     environment:
       MONGO_INITDB_ROOT_USERNAME: admin
       MONGO_INITDB_ROOT_PASSWORD: admin