Reduce librobotcontrol for now and cleanup each board intro

• Restore AI-64 chapter 6, which needs a lot of work
• Changes to most boards index page
• Import some changes off of Deepak's tree (Fire export details)
• Fix Fire forum link in another place
• Fix Fire OSHWA certification ID
• Enable Graphviz
• Fail build on PDF build failure
• Reduce items in ToC
• Try to clean up some of introduction material
• Starting on Linux article based on Tops-Down presentation I started back in 2011 or so
• Clean up some split between BeagleConnect boards and BeagleConnect technology (still has branding issues)