docs: project dependencies

[fyliu]

Dependency

• Switch to alpine base image in Dockerfile #177

Overview

We need to document project dependencies, such as the psql command and manage.py dbshell requires psql, which requires PostgresSQL

Action Items

• add a page or section for project dependencies

Resources/Instructions

from the looks of the Dockerfile, these are the dependencies

• maybe postgresql used by manage.py dbshell
• graphviz used by erd.sh
• Roboto-Regular.tff used by erd.sh

[fyliu]

This should be done after switching to alpine #177 PR #275 so that the dependencies are current to that point.