Sylvia/docs/doc 759

@jmclaus Hey Jean-Michel - I can't get this to work. When I create the component in my toy course, there's just a big blank box where the molecule should be. Can you look through this and let me know if some of the instructions are wrong? Thanks!
I think I figured out what I was missing, and it's pretty much exactly what you're describing...! What might be helpful is to think in terms of, I'm setting up a course and I want to include these great chemistry molecule thingies. What are my options? (well, you have two! one is a component that shows students a molecule, and it's typically added to a unit along with an html component or as part of a problem or what not, so cool, here's the xref, go get 'em. The other option is to make students do some tricksy work and here's the xref to that too.) I know we don't really categorize components and problem that way now, so maybe just a sentence in the intro to each one saying, gee, there's also that other one if you want to consider using that instead...