Establish contribution guidelines for issue labeling, branch naming, and pull request conventions, and add to README

[mattfsourcecode]

Example workflow:

1. Issue Labels: Define a set of labels (e.g., bug, enhancement, documentation, help wanted) and their usage.
2. Branch Naming: Specify branch naming conventions (e.g., enhancement/issue-<number>, bug/issue-<number>).
3. Pull Requests:
   • Require descriptive titles summarizing the change.
   • Include a detailed description of changes, testing steps, and references to related issues.
   • Ensure pull requests link to relevant issues.
4. Testing Expectations: Specify requirements for tests (unit, integration, etc.) to be included in the PR when applicable.
5. Add an example workflow for contributors in the README (e.g., "Create an issue, start a branch, submit a PR").