coderefinery-mooc: Add basic description of CR MOOC style

[rkdarst]

• The main audience here is instructors and those organizing a course, so that they will know what to expect. It also is the first written documentation of the plan to us. The director/producer get training by other means.

• This initial PR is designed to provide a shared understanding of the goal. Then, I go and update the other pages (audiece, helper, etc).

• Review

  • Does this make sense to a new reader?
  • What important aspects are missing?
  • Can we give this to an instructor or organizer and say "This is what we are doing" ?
  • What important information is missing?

[bast]

Thanks for this awesome write-up!