Improve markup and publishing automation

[johan]

How GitHub uses GitHub to document GitHub has some notes on the publishing flow github uses themselves for their automated markdown to Pages rig, which could benefit the #1 pike tutorial too (both for the improved markup for shell commands, and for the manual structure / publishing angle).

The interesting content starts at "Our new setup". Sadly there isn't a lot of meat on setting up the configuration, just a bunch of links to the components and manual sections that enable their rig.