Refactor handbook for development department re-org

• A page for each Sr Director, Director, and Manager
  • Path pattern: /handbook/engineering/development/[sub-department]/[team]/
  • The bracketed values are lowercase and dash-delimited
  • Omit "...department", "...sub-department", and "...team" from the path for brevity
• Use this template: https://about.gitlab.com/handbook/engineering/#team-page-template as a starting point
• Update the code owners file for each URL
• Include the hiring chart sub-template on each page
  • Update the template to include this for me while you're in there

Feel free to delegate and/or fan out.