Replace Service Owner sections with machine-readable YAML team services info

Currently the Service Ownership section at the bottom of each Service page follows a standard format, but doesn't include the team who's responsible for the service.

This Issue is to encode team, people & service metadata in YAML.

Then write macros using MkDocs-Macros to auto-insert:

• Page title
• Sub-title pills for Team, Tech Lead, Service Owner & Service Manager
• Existing bottom section for Service Management
• Content for a contact/teams page summarising each team, their email & services.

Also expose the new services.yml file on an /api/ endpoint for consumption by other services.

This was discussed with other Team Leads in a Teams Discussion.

Tasks

• Create services.yml based on DevOps Team Services and existing service pages in Guidebook.
• Expose that for consumption at <guidebook-url>/api/services.yml
• Define new macro to generate page title followed by pills
• Define new macro to generate Service Management bottom section
• Define new macro + create new page summarising each team's services in per-team sections
• Incorporate "engineers with experience" into YAML & macros
• Make pills hyperlink to lookup (people) or latter new page (team)
• Update service-template.md
• Document new setup in README.md