Showcase for documenting Julia code

This is for Lecture 8 of course https://eth-vaw-glaciology.github.io/course-101-0250-00/

This builds on https://github.com/eth-vaw-glaciology/course-101-0250-00-L6Testing.jl

Then adds documentation via:

• doc-strings
• Literate.jl, see literate-script.jl
• Literate via Github Actions: Literate.yml
  • this auto generates the markdown-file (and figure) car_travel.md upon push to github