Update Docker Compose and Docker ENV Setup docs

Author: No767

docker-compose-dev.yml

@@ -8,7 +8,7 @@ services:
       context: ./docker/pg
       dockerfile: Dockerfile
     env_file:
-      - docker.env
+      - docker-compose.env
     volumes:
       - postgres_volume:/var/lib/postgresql/data
     ports:

docs/dev-guide/intro.rst

@@ -91,7 +91,15 @@ Using Docker
 ^^^^^^^^^^^^
 
 If you decide to use Docker to run the local PostgreSQL server, then a
-pre-built Docker Compose file is provided. Simply run the following:
+pre-built Docker Compose file is provided. Setup instructions are as follows:
+
+1. Copy ``envs/docker.env`` to ``docker-compose.env`` within the root of the repo. Modify as appropriate.
+
+.. code-block:: bash
+
+    cp envs/docker.env docker-compose.env
+
+2. Run the following command to start the PostgreSQL server
 
 .. code-block:: bash