markdownlint + yamllint configs

[ulises-jeremias]

Summary

Static checks for docs and YAML.

CNA mapping

CNA: .markdownlint.json, workflow markdownlint.yml.

Acceptance criteria

• Markdownlint config committed
• Yamllint or equivalent config committed

Blocked by

none

Blocks

none

Reference

Parity matrix (workspace): knowledge/create-python-app-parity-matrix.md
Reference repo: https://github.com/Create-Node-App/create-node-app

Parent epic

#3