Add Contribution Guide

[alexfinnarn]

I usually use Gitflow, https://www.atlassian.com/git/tutorials/comparing-workflows/gitflow-workflow, and feature/[issue-number] for branching. I don't think this repo needs to get fancy with workflows and hot fixing or any of that, but I think it makes sense to provide contributors guidance on how to create branches that can help link PRs to issues.

Acceptance Criteria:

• [x] Decide on how to create branches and link pull requests
• [x] Place notes in some kind of contributor documentation following https://docs.github.com/en/communities/setting-up-your-project-for-healthy-contributions/setting-guidelines-for-repository-contributors

[dmundra]

Ya we probably don't want to get overly strict either. I am fine with simple branch names, not requiring issues be created, and requiring pull requests. We can add branch protection on main branch. I need to get admin access from @bobschmitt-civicactions to set that up.

I think the notes should go in contributing.md file (see https://docs.github.com/en/communities/setting-up-your-project-for-healthy-contributions/setting-guidelines-for-repository-contributors).

[alexfinnarn]

@dmundra I added a draft of a contribution guideline doc based on some things you wrote in this issue as well as my thoughts. To be honest, GitHub Copilot wrote a lot of the doc, lol, and gave a decent outline of the typical sections.

Let me know what you think!

[dmundra]

@alexfinnarn looks great! 🚢 it.