docs(README): update database usage in tests (#1233)

Author: Matthew Fisher

Makefile

@@ -46,9 +46,9 @@ postgres: check-docker
 	docker start postgres || docker run --restart="always" -d -p 5432:5432 --name postgres postgres:9.3
 	docker exec postgres createdb -U postgres deis 2>/dev/null || true
 	@echo "To use postgres for local development:"
-	@echo "    export PGHOST=`docker-machine ip $$(docker-machine active) 2>/dev/null || echo 127.0.0.1`"
-	@echo "    export PGPORT=5432"
-	@echo "    export PGUSER=postgres"
+	@echo "    export DEIS_DATABASE_SERVICE_HOST=`docker-machine ip $$(docker-machine active) 2>/dev/null || echo 127.0.0.1`"
+	@echo "    export DEIS_DATABASE_SERVICE_PORT=5432"
+	@echo "    export DEIS_DATABASE_USER=postgres"
 
 setup-venv:
 	python3 -m venv venv

README.md

@@ -45,9 +45,9 @@ After you have a working Kubernetes cluster, you're ready to [install Workflow](
 
 The application and tests use PostgreSQL. To start a local instance via Docker, run `make postgres` and set the following in your shell:
 ```
-  export PGHOST=`docker-machine ip $(docker-machine active) 2>/dev/null || echo 127.0.0.1`
-  export PGPORT=5432
-  export PGUSER=postgres
+  export DEIS_DATABASE_SERVICE_HOST=`docker-machine ip $(docker-machine active) 2>/dev/null || echo 127.0.0.1`
+  export DEIS_DATABASE_SERVICE_PORT=5432
+  export DEIS_DATABASE_USER=postgres
 ```
 
 ### Python