Add setup for Postgres.

Author: alexmacarthur

postgres/README.md

@@ -0,0 +1,15 @@
+# Enter the Container w/ Bash
+
+`docker-compose exec --user root db /bin/bash`
+
+# Enter the Postgres Shell
+
+`docker-compose exec --user root db psql -h localhost -U postgres`
+
+# Create a DB
+
+While inside the shell, run the following:
+
+```
+CREATE DATABASE mydatabase;
+```

postgres/docker-compose.yml

@@ -0,0 +1,9 @@
+version: '3'
+
+services:
+  db:
+    image: postgres:latest
+    volumes:
+      - ./data:/var/lib/postgresql/data 
+    ports:
+      - 5432:5432