[ci] Setup CI/CD for Python, Markdown.

[vityaman]

Steps:

• Add example doc page in Markdown.
• Add Markdown linter to CI pipeline: https://github.com/marketplace/actions/markdown-linting-action
• Add python hello world project with tests and pyproject.toml.
• Add python libraries and linters:
  • poetry: https://python-poetry.org
  • coverage: https://coverage.readthedocs.io
  • mypy: https://www.mypy-lang.org
  • pytest: https://docs.pytest.org
  • ruff: https://docs.astral.sh/ruff

[vityaman]

That's enough for now.