Doc cleanup in prep for manuscript and repo cleanup/polish

[JamesColl-NOAA]

Cleans up docs and adds polish in prep for manuscript related to #66. See readme and vignettes for raw text, HTML should render once merged in.

[JamesColl-NOAA]

In your review, I'm really looking for the following pieces:

• [ ] Vignette text review as the pre-manuscript intro and methods
• [ ] Throw that reference database crosswalk url in a comment on this function.

[mikejohnson51]

Lets refine this with the internal and peer review of the corresponding paper! Marking as done for now