Include mdBook Documentation on Pi

• Options for getting the deployed docs:
  • [x] Building on the pi (requires installing mdbook binary)
  • [x] Building and serving on the pi (requires installing mdbook binary + service)
  • [x] Downloading pipeline artifacts
• Implement download in ansible (7a8f9bde)
• Add desktop shortcut (37b952c5)
• Fix edgecase for running playbook on light image