Document how to work with development seed data

[arirawr]

🐞 Problem

No documentation for working in the development environment and mocking things like users with X PRs.

🎯 Goal

Provide examples for various data states so contributors can develop without SQL knowledge.

💡 Possible solutions

Provide step-by-step instructions (including SQL snippets) for editing development environment seed data in README or CONTRIBUTING.

📋 Steps to solve the problem

• Comment below about what you've started working on.
• Add, commit, push your changes
• Submit a pull request and add this in comments - Addresses #<put issue number here>
• Ask for a review in comments section of pull request
• Celebrate your contribution to this project 🎉

[arirawr]

I will work on this in the next little while unless someone would like to grab it! I just went through setting up the dev environment for the first time while working on #2141 and it would definitely not be fun for folks who haven't used SQL.

[andrew]

Thanks for tackling this @arirawr!