Support Rmd

[mmaelicke]

notebook-classroom should also knit Rmd files to .html. This should be solvable within the workflow file.

[mmaelicke]

I transferred this from ntoebook-classroom.

This should not really be a problem and rather be solved within this sample repository than the application itself.

The additional steps in the workflow file include:

1. install the dependencies for knit (assuming it will need pandoc). I see three options here:
   a) sudo apt-install everything and stick to ubuntu workflow os
   b) install conda and install r-essentials + dependencies
   c) check dockerhub for a docker image (or create one) to use a docker-action for knitting
2. knit the Rmd files. I am not sure if they (unlike jupyter notebooks) get executed automatically
3. the output is .html, so from this point on there is no difference anymore

What I am not sure about:

• How do .Rmd compile into slides
• binder links will not work as they need to load .ipynb files. But maybe Rstudio has something similar that could be included (would be a ntoebook-classroom issue though)

@modche I saw you star the repo ;)
Do you have an idea about the two last points? Interested in implementing and testing? I'm sure you have some awesome lecture-like Rmd around.