docs: add an example clinical trial report

[machow]

@gshotwell mentioned it could be cool to create a shiny template for reporting clinical trials. Opening this issue to track creating some docs around this kind of thing.

Docs to write

Let's try writing some docs in this order:

1. A simple example (not an app) on Great Table's doc site
2. A shiny app (or template) that could go somewhere on the shiny docs (e.g. gallery, examples, or their templates repo). (Worse case, we could put it in our docs, etc..!)

Finding a good example

Are there any good examples of clinical reports, etc.. written for R gt?!