fix: Fix headers in markdown to reflect when its limited to date range

[zkoppert]

Pull Request

fixes #143

Proposed Changes

Update contribution tables in both the README.md examples and in the functional code markdown.py files, along with corresponding changes to the test cases in test_markdown.py. The goal of this change is improving the clarity and accuracy of contribution data by including date ranges for commit counts and specifying when the date reange is not limiting the results for that column.

Readiness Checklist

Author/Contributor

• If documentation is needed for this change, has that been included in this pull request
• run make lint and fix any issues that you have introduced
• run make test and ensure you have test coverage for the lines you are introducing
• If publishing new data to the public (scorecards, security scan results, code quality results, live dashboards, etc.), please request review from @jeffrey-luszcz

Reviewer

• Label as either bug, documentation, enhancement, infrastructure, maintenance or breaking

[jmeridth]

Nice add.