Added contributor.md and updated code block styles to better fix github markdown patterns

[MSeal]

Adds contributor markdown and cleans up some of documentation. This is an effort as a precursor to engaging the community for completely.

This adds a Contributor.md file, changes the setup instructions to include virtual environment, removes the python2 vs 3 implication for older OS defaults, changes code references to code blocks, and adds some cross md file references where relevant.

Checklist

• [ ] Contains customer facing changes? Including API/behavior changes
• [ ] Did you add sufficient unit test and/or integration test coverage for this PR?
  • If not, please explain why it is not required
  • Documentation change only, no behavior or code differences

References

JIRA:

Test & Review

Open questions / Follow-ups

This had been discussed internally ahead of time, nothing surprising for confluent reviewers should pop up.

Initial changes were drafted with cursor then hand touched and reviewed to ensure intent and quality. Recommended that instructions are clear and no typos or mistakes are present in a read through.