Document the build process

[mr-c]

See #148 (comment)

https://carpentries.github.io/lesson-example/
https://carpentries.github.io/curriculum-development/technological-introductions.html

Explain the changes we made for this user guide

• carpentry is cwl
• others?

[tobyhodges]

I'll try to take a look at this over the next week or two.