Reconcile skeleton.Rmd files

[kelliemac]

Description

I noticed that there were some inconsistencies between the visc_empty and visc_report skeleton.Rmd files. I attempted to resolve those and also to keep the visc_empty skeleton.Rmd as minimal as possible.

Question for reviewers:

1. Does the visc_empty skeleton.Rmd contain all of the basic elements?
2. Is there anything in the visc_empty skeleton.Rmd that could be simplified further?
3. Are the changes to visc_report skeleton.Rmd acceptable?

Related Issues

Related to https://github.com/FredHutch/VISCtemplates/issues/203

Checklist

• [ ] This PR includes unit tests
• [ ] This PR establishes a new function or updates parameters in an existing function
  • [ ] The roxygen skeleton for this function has been updated using devtools::document
• [x] I have updated NEWS.md to describe the proposed changes