Link config-derived parameters to input documentation

[zsusswein]

I'm not totally sure whether to do this inline or in a markdown doc. If inline, I could extend it everywhere using Roxygen2 inheritance.

[zsusswein]

Saw something over the weekend in the bridgestan docs. We can document everything in the roxygen docs, render to Rd, and then use rd2markdown to render to plain markdown. I think we could then check this into version control and link in the readme.

[zsusswein]

The rd2markdown folks have examples in their readme of auto-including rendered Rd docs in the Readme by using a readme.Rmd and calling the function. @seabbs I remember you discouraging the Rmd approach as potentially adding a bunch of size bloat to the repo? Was that specifically to figures/model fitting or something you recommended avoiding in general?

Our readme is already getting pretty long, so I might go with linking out either way.

[zsusswein]

Closed by #99